N9EWO Reviews :
ATS-25 / ATS25 /
LW / MW / SW / FM DSP Receiver
(with Bernard Binns FREE 4.0 Firmware review)
HUGE "Thank You" to Dean B. as without his help, this review would NOT be here.

The cute ATS-25 Chinese LW / MW / SW / FM DSP receiver.
2.4 inch "Touch" LCD with internal lithium ion polymer rechargeable battery.
Front panel model markings vary between ATS-25 or ATS25.

It's actually usable IF one receives a properly made sample,
 but that varies greatly from internet reports. High possibility of
receiving a dud makes it less desirable. Updating the VERY
confusing Arduino firmware is only for the computer
 tech savvy. For most it will be a no-go !

Is this ANOTHER Chinese disaster "pot luck" receiver to pass up
 by who knows made by many DIFFERENT "knock off" manufactures ?
  If you don't care for dealing with a unfinished project receiver
we say it's best to spend your money elsewhere !

UPDATE : Russian firmware improves this receiver greatly,
 please see separate reviews down this page.

Is a variant around that has no tuning knob (just a smooth front
"rub on the panel" to tune), this is unacceptable to the author (we say avoid).
We have also seen this variant sold in a bright pink color case.  
(this version was not tested)

Country of Origin  : China
"Test Sample" Serial Number : NONE marked
Firmware Version Tested :  Beta V2.? (later version of Beta V2 ?)

Test Antenna's (all outdoor) :
Comet DS150S Discone Antenna (30 ft height)
RF Systems MLBA-MK2 long wire (55 ft length - 24 ft height at peak)
Comet H-422 Dipole (24 ft height - Straight Configuration)

N9EWO's Review on the ATS-25 DSP Receiver (beta V2.0 firmware)

- Frequency coverage : LW 149 ~ 522 kHz, MW 520 ~ 1710 kHz, SW 1710 ~ 29999 kHz, FM 64 ~ 108 MHz
- Very good selectivity (all bands).
- Well chosen bandwidth selections.
- Anodized aluminum case - top and bottom (see con).
- Decent overall sensitivity on RESONANT OUTDOOR antennas with coax feed line (see con).
- Double sideband synchronous detector that  is very useful (appears ONLY available with Beta V2 firmware).
- Excellent tuning step choices.
- Large top mounted internal speaker (see con).
- Robust BNC Antenna connector.
- Useful digital battery voltage indicator (see con).
- Very handy audio mute button.
- SSB fine tuning function (25 hz steps)
- Good ECSS reception.
- Broadcast and Amateur radio band presets. 
- RDS (Radio Data  System) works adequate with proper sensitivity (see con).
- FM Stereo with headphones (see con and text).
- Decent battery life.
- Dynamic range while on the fair to poor side was better than expected.
- Good size main tuning encoder knob (see con).
- Direct keypad entry that also allows kHz entry on SW bands.
- Very good and useful "Seek" function.
- Generally stable (except for warble issues, see con and text)
- Cool operation.
- Audio quality OK on wider bandwidths (see con).
- Has potential of improved performance for those who are familiar with Arduino.

- Some samples suffer from reversed tuning encoder wiring (manufacturing blunder).
- Some samples suffer from malfunctioning digital battery meter.
- Front and rear panels made from painted PC Board material.
- No separate volume control.
- Whip antenna use not possible due to excessive circuit noise (OK for strong signal use FM band).
- NO ESD static front end protection.
- Inconvenient rear location of power switch and headphone jack.
- Pain to deal with FM Broadcast  / LW-MW-SW rear switch.
- Local FM Broadcast breakthrough into the SW bands (noticed in the 19 meter SW band at test location / antennas).
- NO front end bandpass filtering on ANY band (any local strong signals will swamp it).
- Weird tone on SSB and Sync modes (curable see text).
- So called AGC and attenuation functions / adjustments are weird !
- No REAL AGC adjustments.
- Warble issues in SSB and Sync modes with test sample (see text).
- No LCD backlight brightness adjustment or OFF.
- Poor LCD touch screen sensitivity.
- Headphone output jack (with test sample) dead on LW / MW and SW, only operates on FM band (sample defect ?).
- Clipping AGC distortion on SSB and Synchronous Detector mode (however not as bad as on many Tecsun receivers).
- Very annoying LOUD popping noises when selecting mode, bandwidths, etc.
- Memory channels can only be programmed via
Arduino (with Beta V2 firmware).
- Internal lithium ion polymer battery not easy to replace.
- Mode and Bandwidth selections don't always take (see text).
- Receiver noise floor and audio loaded with excessive hiss (especially on SSB and Sync modes).
- Annoying tuning "chuffing" (some may call this tuning muting).
- Detented tuning knob encoder has fair to poor feel and is slightly wobbly.
- Internal speaker is very crudely glued onto case.
- Useless over reading S-Meter.
- RDS has a very short data line.
- Uses bridged (BTL) MD8002A speaker audio amplifier IC (MUST be kept isolated from chassis ground or it will get damaged).
- No printed or PDF operational manual.
- BNC connector used does not get tight enough with some male plugs (so is why whip antennas flop around). 
- Highly variable "pot luck" quality control.

Developers of the ATS-25 / Open Source Firmware

There are 3 people who are involved with the development of the ATS-25. Being a open sourced receiver and with it operational firmware being based on 
"arduino" are now others that are now offering different GUI / performance / operation features (see text below).

Those 3 folks who made the ATS-25 happen are :

Ricardo Caratti - PU2CLR (Brazil) FIRMWARE
Gert Baak - PE0MGB (Netherlands) - HARDWARE
Thiago - BD7JPY (China) -  PCB / CABINET

Size - Feel - Strange Construction / Internal Battery Pack / BNC Antenna Connector

As with many Chinese radio products, there can be MANY different factories manufacturing the same marked model. This does not mean that they have the same identical operation, quality or actual parts inside even IF they LOOK the same outside ! So keep in mind the review text below is based on OUR test sample and may vary greatly.

The ATS-25 (also marked as the ATS25 by some factories) size is 120 x 115 x 48 mm (4.72 x 4.53 x 1.90 inches) not including the large front tuning knob. It is housed in a attractive looking package (sort of like a micro communications receiver). Where it gets weird is what the cabinet is made out of. The top and bottom covers are nice black anodized aluminum. Whereas the front and rear panels are of a fiberglass PC board material (painted black) are screwed to the bottom and top covers.

There are no feet on the cabinets bottom. Some sellers include 4 SMALL stick on feet, some do not. Ditto for including a USB C connecting cable and a short BNC antenna. We received a BNC antenna with the test sample, but it was near useless as it did not tighten up properly on the connector. It flopped around like a dead fish. Was the same thing with other tested BNC whip antenna's, so it's the actual connector on the receiver that is the problem here. As we will cover later the whip antenna is not of any real use anyway. This is NOT a set for use with any attached whip antenna (perhaps for strong station FM broadcast use) !

Uses a
Internal 2000 mah non-replaceable lithium Ion polymer rechargeable battery (about 140 ma current draw).It was glued to the bottom of the cabinet along with soldered wires to the rear PC board (see internal photo below).

ATS-25  **** N9EWO Current Consumption Testing ***
Tested Current Consumption at 3.6 Volts   Meter: Fluke 77 IV   f: 7400 kHz
(volume control set at normal level) Firmware : V2.0 (later) Beta

***** ALL MODES *****
141 ma

Battery Meter / S-Meter a Wash Out

A very useful battery meter is provided and will gave us a pretty good idea when it's time for recharging. NOTE : With some firmware beta version 2.0 samples the battery meter does not function (sits at ZERO). Obviously this is firmware bug.

The S-meter while indicating some relative signal strength, is very unresponsive and near useless. What it does indicate is either too high or near not at all.

Uses the Si4732 "One Chip" DSP receiver on a chip / RDS / No Front End Bandpass Filtering / No Antenna ESD Protection

The heart of the ATS-25 is provided by the SkyWorks Si4732-A10 DSP receiver integrated circuit. Plus there are 2 audio amplifier IC's. One is for headphone audio while the other is for speaker output. One 1/8 inch stereo headphone jack is provided on the rear panel. Strange part here this jack ONLY operates with the FM broadcast band (in stereo). We consider this a MAJOR drawback !

RDS (Radio Data System) is a chip feature and works well (even weak signals trigger it fine). Sadly the data line on the LCD is short so has to do some pretty major and slow scrolling.

No front end filtering can be found. So if you have local Amateur or Broadcast stations near by, you most likely will get swamped. One can easily add external filtering or preselection, but of course this is  pain to have to deal with. There is also no static protection, so take steps to avoid external outdoor antenna static damage.

SkyWorks Si4732-A10 DSP receiver integrated circuit.
(click on photo for larger view)

Eye Catching Color 2.4 inch Touch Screen LCD / Poor Touch Sensitivity / No Backlight Brightness Control

The 2.4 inch color LCD is indeed an attention getter. While it looks great the touch sensitivity is dismal at best. However one gets used to this trait in time. Weirdly when the "Direct Keyboard Entry" is used it's takes much less pressure (more like what it should be).

LCD has no backlight brightness adjustment with the test sample. Reports have indicated this is because the components that were for this function have been left out. This is not so disconcerting as it's not overly bright even during night time use.

Tuning Knob (Encoder) / Tuning Methods / Excessive Chuffing

One large tuning knob (mechanical encoder (with sloppy feeling soft click detents) does tuning and volume control functions. Pushing it in for second selects the SSB "Fine Tuning" (so called BFO) mode as does BFO button on the LCD. It has a low cost "cheap feel" along with some wobble.

WARNING : Are MANY reports where the tuning encoder works backwards with some samples (clockwise rotation tunes down and counter clockwise tunes up).

There is a variant model floating around that has smooth slider tuning knob (no physical knob, no tested). See photo above.

Pretty excessive tuning "chuffing" (muting) as does the Tecsun manfactured County Comm GP-7 SSB (from watching videos)

Frequency Coverage / Modes / Available Bandwidths / Tuning Steps
(PLEASE NOTE : As based with the tested
Beta V2 firmware)

Frequency Coverage :
- Long Wave 149 ~ 522 kHz
- Medium Wave 520 ~ 1710 kHz
- Short Wave (no gaps) 1710 ~ 29999 kHz
- FM Broadcast 64 ~ 108 MHz

Available Modes (LW / MW and SW) :
- AM
- SYN (Double Sideband Synchronous Detection)

Available DSP Bandwidths:
- LW/MW/SW :
          AM Mode : 1.0, 1.8, 2.0, 2.5, 3.0, 4.0, 6.0 kHz
          SSB and SYNC Modes : 0.5, 1.0, 1.2, 2.2, 3.0, 4.0 kHz
- FMBC : (One fixed unknown value)

Tuning Steps
- AM, SSB and Sync Modes : 1 , 5, 9, 10 kHz
- So called BFO (fine tuning) : 25 hz steps
- FMBC : Normally 100 kHz. (UPDATE: iF direct keypad entry is used then after the "Knob Tuning Steps" became 10 kHz (or 50 kHz , it strangely varied). Resets back to 100 kHz steps once power is cycled.

The tuning steps and DSP bandwidth selections were well thought out. With the FM Broadcast band there is no way to select only the 88 to 108 MHz segment (see Binns 4.0 software update review below). So the wrap around goes from 108 back to 64 MHz.

Weird so Called AGC-Attenuator /
Dynamic Range

We see the AGC button on the main screen. Turning this on and off made no noticeable differences to the AGC decay rate etc (AGC OFF is surely not valid here). However it did cure the heterodyne bug as covered elsewhere this review. In the NEXT screen, there is AGC adjustment from 1 to 37. When selected it says "ATT SET". Admittedly when rotated up in number it has the effect of a very low amount of attenuation as it too can cure overloading. We were unable to figure out what is really happening here ? So confusion aplenty on this function.

We were expecting not so great dynamic range given the use of the Si4732 as connected to a decent resonant outdoor antenna. We were pleasantly pleased that in real use overloading only occurred during peak listening in the 40 meter band at night (and a few other rare situations). It only took a small amount of external attenuation to cure the overloading. UPDATE : Very rarely it would become awash with spurious signals and even with 20 db of external attenuation AND maximum ATT SET did not clear this up. Is another one we were unable to get down to what was happening here (overload yes, but it was just plain weird overloading).

Local FM Broadcast Breakthrough into the SW Bands

We detected in the 19 MB shortwave band a bit of local very strong FMBC bleed through. Mind you this can be cleared up with a external filter. Being the ATS-25 lacks ANY front end filtering, this can be near expected. Mind you this was not at any excessive level at our test location.

Good Sensitivity BUT / Decent Selectivity / External Antennas ONLY - Display Noise !

External antennas with shielded coax cable are ONLY to be used with the ATS-25. The display and circuit noises make it impossible to receive signals using any whip attached or close in antenna's. The exception is the FM broadcast band where you get away receiving local stations. If one wishes to use the receiver as field portable, better have a length of shielded coax cable a good 10 feet away before any antenna is strung up. Other wise it's "errazzzzz" of noises.

Once connected to a decent outdoor antenna using coax feed line it's sensitivity is quite good (no less sensitive than any other average HF receiver). But even receiving a strong LW/MW/SW signal there is excessive hissy-ness that lurks (more on this later).

DSP selectivity pars better and with proper values provided. However in AM mode the bandwidth appears to be about double than what is displayed (SSB mode is closer to what is shown). For example : AM Mode 6 kHz is more like 10~12 kHz.

Seek Function That is Most Useful

In the NEXT (second page) of MENU selections there is a SEEK >(up) and SEEK <(down). This works well however it stops when it finds a signal and must be pressed again to continue. There is no timed resume function.

Disconcerting Operational Quirkiness / Microphonics

For the most part the ATS-25 is fairly stable it operation. But not entirely. A strange consistent bug happens when we say switch to SYNC mode and select different bandwidths. It switches to the SYNC mode OK, but bandwidths don't select or display properly. The pain in the rump fix here is to switch to LSB or USB mode for a second and make the desired bandwidth selection and and then back to SYNC. This chore gets around the firmware bug, but is very disconcerting.

For another MODE quirk, sometimes when we are in Sync mode and switched over to LSB or USB, it takes a trip in AM in between before it actually switches over. Otherwise it hangs in Sync (with LSB or USB being displayed). 

Additionally in SSB or SYNC modes if we tap the cabinet (of bounce the case on the tabletop), a nasty warble was detected. This can also be a problem if the antenna connector is loose (or a loose fitting BNC connector). Also intermittently in Sync mode it would become unstable including warble. Tuning to the next station this unprovoked warbling disappears. But again this is intermittent and for the most part is not not a severe drawback. Weird is right, and yes it is tuned to the center of the carrier !

Large Top Mounted Speaker / Audio Quality OK With Circuit Hiss / POP Sounds

A large approx. 3 inch (cm) top mounted speaker is used. Even with it's large size it has a hollow sound to it. The speaker is attached to the top cover using some ugly white glue. Mind you it works, but is just not so eye pleasing.

As covered above, there is a pretty high amount of circuit hiss in the LW / MW / SW bands.

Very annoying LOUD popping sounds when selecting mode, bandwidths, etc. Also at power up one LOUD pop followed by a few more before it comes to life. Also when selecting MODE ...you guessed it more loud pops.

SYNC Detector-SSB Modes Have Clipping Distortion / Decent ECSS / Weird SSB BFO Adjustment

The ATS-25 with the tested firmware has a double sideband "Synchronous Detector". It performs generally well holding lock fairly decently. Very weak signals do not par as well, but other times it can help greatly to pull out audio from weaker signals (even with it's excessive hissy trait).

UPDATE :  It appears from watching "You Tube" videos that the Sync mode is ONLY available with the tested Beta V2 firmware.

As long as you use the wider bandwidths on SSB Amateur signals, AGC clipping distortion is limited with normal strength signals (ECSS is not a problem at any time). But please note the narrower you go the nastier it becomes. With any super strong SSB signals, AGC clipping distortion now becomes a real problem. Yes, ECSS is indeed pleasant with the ATS-25 (and at this price point this was a surprise). Stability is adequate when it's working correctly.

The weird BFO adjustment is selected by pressing the BFO button on the LCD OR pressing the main tuning works as well. This is not really a BFO adjustment per say, but is a fine tune control. It is in somewhat course 25 Hz steps. Downside is that it's inconsistent as takes say + 25 hz on one end of 40 meter Amateur band and the other end of the band it's -50 hz to be on frequency. That's is downright weird !

Annoying and Strange SYNC-SSB Heterodyne (royal pain in the rump)

Here is a strange trait with a receiver we have never encountered until now.
When in USB, LSB or Sync modes there is a very disconcerting background tone that appears along with the received signal. If after tuning and setting the bandwidth / tuning steps etc., if we THEN tum OFF the defacto AGC this tone disappears completely. If I adjust the tuning / bandwidth / mode the tone reappears and then need to turn off the AGC once again. Adjustment of the  BFO , Volume / Mute does not set the AGC and this annoying tone back on.

NOTE : This bug appears to be variable and not on all samples. Firmware bug ?

 N9EWO MP3 Audio Recording :
ATS-25  Strange SYNC-SSB Heterodyne (see text) 

N9EWO MP3 recording of the strange LW / MW / SW "SYNC / SSB Mode Heterodyne"
Once a station is tuned in using SSB or SYNC modes, one can hit the AGC key and this annoying tone disappears as switched on and off in the recording. Well until you hit the tuning knob or other buttons and it then returns.

PLEASE  NOTE : This bug appears not to affect all samples. It may sound like microprocessor noise in this recording (due to using a mic next to the speaker), but it's not. This recording also clearly shows the ATS-25's hissy audio.

Headphone jack did NOT operate with test sample on LW / MW or SW bands (sample defect ?). FM broadcast band it functioned but with weak shrill output. Recording was made using a microphone placed near it's top mounted speaker.

Headphone Jack of No Use on Test Sample (sample defect ?) - Low Level / Look Out  : BTL Audio Amplifier

We need to stress AGAIN the rear mounted 3.5 mm stereo headphone jack was DEAD on the ATS-25 test sample on the LW / MW and SW bands. Worked only on the FM band and was with fair low shrill audio.
This is just plain unacceptable even as a project receiver. NOTE : Appears this could be a defect with the test sample ?

TIP : If we carefully placed the rear antenna switch in between (middle), LW / MW and SW audio was heard from the headphone jack qith the test sample. A strange work around it is and could put stress on the switch after awhile ? Mind you it is a bit tricky to place this switch in middle position.

There are 2 audio IC amplifiers being used in the ATS-25 (at least on the test sample). The APA2308 is a "Stereo" Class AB Headphone amplifier followed by a "Mono" 3 watt max MD8002A that drives the 4 ohm top mounted speaker. This is BTL (bridged) type amplifier. It MUST be kept isolated from chassis ground or otherwise...POOF it goes. So you have been warned !

Memory Channels Only Programmable via

We see a "Preset" button on the front panel. OK the user assumes can program our favorite frequencies easy. However not so fast ! Turns out that ONLY way to enter memory channels is by updating the firmware via arduino. There is no way to enter memory channels in a standalone configuration. However the Russian version 4 firmware allows easy memory channel programming from the front panel, see separate review down this page.

The ATS-25's rear panel shows it's BNC antenna connector
 (much improved over a less robust SMA connector).
The receiver POWER slide switch is inconveniently located
on the rear panel as Is FM / LW-MW-SW antenna switch.
Sorry, no "Line Out", but we do have a PLASTIC headphone jack.

(Sadly headphone operation was DEAD on LW / MW and SW,
 only worked with STRONG FM Broadcast signals. Sample defect ?)

Arduino Based and Firmware Updates Not Easy For Most (Much Improved Binns Russian 4.0 / 4.10 tested, see below)

Firmware version 3.1 (July-27-2021) Less tuning chuffing. Sync detector removed.
Firmware version 3.3 (Nov-02-2021) 100 and 10 hz digit and CW mode have been added.
Firmware version 3.4 (Nov-23-2021)
Firmware version 3.5 (Mar-03-2022) See the GitHub page here for additional firmware information

Firmware version 4.0 and more featured 4.10 from a Russian author (see full review below). Features and GUI much changed over the 3.x versions ! Allows for standalone memory channel programming. Simple (not real time) band scope. Has many user adjustable menu adjustments.

Starting with firmware 3.1 the GUI was drastically changed.
 Updating the Arduino based firmware is not possible for most.
No more Sync mode. Uses a micro USB C connector.

Internal Photo of the ATS-25 Test Sample.
2000 mah lithium ion battery glued onto the case floor.
Soft "click" push in type mechanical encoder is used. (N9EWO Photo)

For Those Who Are Not Computer Tech Savvy, Best to Look Elsewhere with Beta V2.0 firmware Installed / Watch The Price

If you don't care for dealing with a unfinished project receiver, we say it's best to spend your money elsewhere ! If you can accept receiving a sample with older lesser performing firmware, It might be useful and fun to you. With it's eye catching colorful LCD display, it's usable depending it's connected to a decent resonant OUTDOOR antenna fed with shielded coax cable. The strange disconcerting heterodyne with SSB and Sync modes is a pain in the behind, but as covered above there is a way around it. Keep in mind this receiver will not equal any better tabletop set or BETTER portable (not even close) ! But at it's price point that can be expected.

UPDATE : Please see the review below with the receiver loaded with much improved Binns FREE 4.0 firmware.

The ATS-25 is available from MANY Chinese vendors on eBay and Amazon (do your own searches). WARNING : Be sure and do not overpay for any ATS-25 receiver (or a variant of). Prices are all over the place. We say anything much over $ 100. US Dollars is excessive for what it is (it becomes not worth it).

Dave N9EWO
N9EWO, all rights reserved
ver 5.6

N9EWO's ATS-25 Last Word
As you read above with the mostly negative comments , I have to classify the ATS-25 as a radio paperweight. Been back and forth on this in my mind but have decided it’s one to avoid (at least with the with first tested version 2.0 beta firmware).

[UPDATE : See Bernard Binns 4.0 firmware review below. This improves the receiver greatly.]

I will say it was fun to play with and the color touch LCD is most attractive, but the overall performance and what you need to do to achieve it is just a sour experience ! It is sensitive on MW and SW using a resonant OUTDOOR antenna (using coaxial feed line).
FM broadcast was very sensitive too.
Mind you it has certain plus merits over most current Tecsun receivers (less SSB / SYNC clipping distortion and usable wider bandwidths on Sync). But for the most part it’s a unfinished "radio / computer geek" project.

Perhaps fun for the computer savvy person who likes
to deal with always ongoing firmware changes and with a strange process to boot. However for the mainstream radio listener or consumer.....we say forget it !
The dead headphone jack (only working on the FM Band) was just ANOTHER HUGE whammy with the test sample that made me swing more to the "thumbs down" side of the fence of my general view of this receiver (this appears to be a sample defect ?). The strange heterodyne in SSB and Sync modes was another disconcerting deal breaker (even if it can be controlled but is just ANOTHER pain to have to deal with). This bug was improved with the  software update as covered below.

Sorry......but with firmware Beta V2.0 it's another "Caveat Emptor" (buyer beware) on this one.

Dave N9EWO
N9EWO, all rights reserved
ver 3.6

ATS-25 LINKS (All Subject To Change Without Notice)

Facebook User Group (Public) : Si47XX for Radio Experimenters

Groups.io si47xx page (Public)

Firmware 3.x -Touchscreen - Arduino

Bernard Binns Firmware 4.0 - ATS-25 - Arduino see below

You Tube Video's

ATS-25 Si4732 How to UPDATE firmware and Teardown ATS-20 ATS-25

ATS-25 has definitely better performance than the ATS-20 when tuning close to a strong signal

You Tube Video's (Russian Firmware 4.x)

Firmware 4.0 - ATS-25 (from Russia) see below


N9EWO Review :
ATS-25 / ATS25 / ATS25+
LW / MW / SW / FM DSP Receiver
with Bernard Binns 4.0 firmware (open source - free)
HUGE "Thank You" to Dean B. as without his help, this review would NOT be here.

Bernard Binns improved version 4.0 firmware for the ATS-25.
We have seen it sold loaded with this improved firmware as the "ATS25+".
Not that this fixes all of it's bugs (it doesn't), but does make for a more much attractive receiver
but for only if one purchases it with THIS firmware pre-installed. Most will not be able
to update it's
Arduino firmware using a Windows PC as it's not for the faint of heart.
Sadly lost Synchronous Detection mode with this updated firmware, but gained 75 front panel programmable
 memory channels / spectrum display (not real time) / lesser SSB het issues and more stable operation. (N9EWO Photo)

Country of Origin  : China
"Test Sample" Serial Number : NONE marked
Firmware Version Tested :  4.0 (Bernard Binns from Russia)

Test Antenna's :
Comet DS150S Discone Antenna (30 ft height)
RF Systems MLBA-MK2 long wire (55 ft length - 24 ft height at peak)
Comet H-422 Dipole (24 ft height - Straight Configuration)

NOTE : Antonino Russo released a modified 5.2 version (not tested). This is his version of 4.0 and only implements full RDS data (station name - rds news - rds time). Antonio's modification is included with Binn's updated 4.1 version, see below.

N9EWO's "ATS25" (ATS25+) DSP Receiver Review with Russian 4.0 firmware.

As compared to later version V2.0 Beta firmware as tested above.

- Very annoying tuning "chuffing" (muting) greatly reduced.
- CW mode added.
- 100 and 10 hz tuning steps added with display digits (SSB / CW modes).
- 75 "front panel programmable" memory channels that store frequency, mode, tuning step. Also can store alpha tags (see Con).
- Generally more stable operation.
- Strange SSB heterodyne issue now reduced and reversed (no longer a Con).
- Volume control adjustment now also available by pushing in the tuning knob once.
- RDS display is now larger (see Con).
- Very useful Spectrum Scope feature added (see Con).
- Touch screen sensitivity improved.
- Important operational toggles available in added Menu.
- Slightly less "hissy" audio.
- SSB clipping distortion slightly Improved.
- Vertical screen operation.
- RF attenuator now properly marked with improved performance.
- Improved S-meter performance (see Con).
- FMBC frequency coverage select (with wrap around).
- Additional FMBC bandwidths.
- Additional FMBC tuning step (10 kHz).
- Selectable screen saver.

- Most will not be able to update it's Arduino based firmware.
- Intermittent DSP artifact noises with weaker signals.
- Annoying "Digit Backlight" (on as default, but can be turned off in menu).
- Double Sideband "Synchronous Detector" mode removed.
- Memory channel entry sometimes OFF frequency (intermittent bug).
- Alpha Tag entry extremely difficult due to poor character advance selector (pushing in tuning knob).
- RDS text very tight just under frequency display and bad color choice (see text).
- Spectrum display not in real time.
- Preset BAND and HAM limits not well thought out (are near useless).
- Battery voltmeter no longer operational (it had worked fine with beta V2.0).
- S-meter while now more useful, still over reads.
- Adjusting bandwidths in SSB modes sightly effects BFO setting (changes around 25~50 hz).
- Adjusting ATT affects BFO setting.
- While being much more stable over the beta V2.0 firmware, some strange happenings still occur.

If you are Familiar with Arduino, of course OK to Purchase a Old Version (and just update it).

For anyone familiar with arduino, updating the ATS25 will be a near piece of cake. If you are not (which is most of us), then ONLY purchase the ATS-25 with this firmware pre-installed. WARNING : Most samples sold as I type this come with the beta 2.0 version firmware as reviewed above. We see the 4.0 version sold as the ATS25+, but as it goes with any Chinese radios....that could very well vary.

Tony Albus's Video goes into the procedure in detail (You Tube Video here). But for many this still will be a row of ?'s. WARNING : For the Russian version tested here the procedure is slightly different. Please see the "update firmware" text file in the in 4.0 instructions.

Bit More Sensitive Touch Screen / Improved RF Attenuator

Touch screen is a bit more sensitive, that is takes less pressure to make it happen. The RF attenuator is now properly marked as ATT and actually gives improved performance. This is important as it greatly helps to tame overloading, and it usually only took just a bit to do that with our tested outdoor antennas.

The very useful volume control time out feature takes a few seconds longer before resetting back to tuning as compared the beta V2.0 firmware (good to see). An additional plus is now one can tap the main tuning knob to select volume (now twice for BFO).

Improved Layout / Annoying Digit Backlight / Improved S-Meter / Lost Battery Voltage Indicator

The overall GUI has been improved including more on screen selections and better management. Only little snafu is the RDS display while being larger over beta V2.0, is very tightly given just below the frequency display in a not so easy to see purple color.

There is what is called a "Digit Backlight" that shows the frequency display with a old school digital look. But we found it very annoying and made it hard to view. Thank goodness this is easily turned off.

At least the S-Meter has been improved enough to be now at least marginally useful. Still over reads but now at least has some usefulness.

Battery voltage meter that was working just fine in beta V2.0 firmware main screen, is not with 4.0 (voltage reads near ZERO). However IF I drop into the INFO screen the correct battery voltage is shown properly in the list. This is of course a firmware bug (and NOT a hardware issue with my test sample).

Much Reduced Tuning Chuffing (Muting) / New CW Mode / 100 and 10 hz Tuning Steps Added

The nasty excessive chuffing (some call this muting) when tuning with the main knob has been greatly reduced. A touch still remains (more so in AM mode), but this is a HUGE improvement indeed ! Also a CW mode was added (available bandwidths : 0.5 and 1.0 kHz). Also in SSB and CW modes, 100 and 10 hz tuning steps / display were added.

75 memory Channels with unusable Alpha Tags / Memory Entries can be OFF

Another HUGE plus addition is the 75 memory channels that are programmable from the front panel. These store frequency mode and tuning step. Additionally each memory channel can have Alpha Tags. However in practice entering theses tags is extremely frustrating and not worth the bother. It's not having to dial the letters with the knob, but it's advancing to the next charterer that is the problem. This is done by pressing in the tuning knob for a SECOND. Well that toggles the fixed Russian FM memories more than not which voids the entry entirely.

Also another bug unearthed is with memory channel entries in general. They were 16 kHz low when it happened. The really strange part is that this "being off" varies and is not consistent (and sometimes it works just fine). Anyway , we are glad just to see the receiver to still have useful memory channels. This eemmed to happen more with 9 Mhz entries (but not always).

TIP : To help stabilize BFO to more exact previous settings, tap the BFO mode (button) and then just exit back out at power up. 

User Defined 4.0 "Menu" Selections

Here is something totally lacking with the tested Beta V2.0 firmware, a way to select user defined functions and features. Some of these require hardware modifications and added parts (like the backlight and beeper), however most are not. Use the tuning knob in SETUP to select these pages. Here is rundown of those with the tested 4.0 firmware :

User Defined 4.0 "Menu" Selections (subject to change)

- FM start 64 MHz (or at 88 MHz)
- Seek AM 1 KHz
- RDS only FM Button
- Digit backlight (requires hardware modifications / added parts)
- Memo in preset
- Retro language RU
- Screen Saver
- Display light off
- Saver time in min (2, 5, 10 and 30 minutes)
- Vertical Screen
- Minimum scale
- Maximum scale
- Auto scale
- Scan accuracy
- Battery show
- Beeper on (if provided on hardware)
- Bright disp power
- Load default Memo
- Reset to Factory (does NOT clear memory channel data)

SSB Clipping Distortion Slightly Improved / No More Sync Detection / BFO Frequency Varies Slightly with Bandwidth  / Slightly Less Hissy Audio

SSB audio AGC clipping distortion performance is a bit improved. It can happen and more so with stronger signals and increases with narrower bandwidths. But is still MUCH more tolerable over many (most?) other current Chinese portable SW sets that have SSB mode (including most current Tecsun and the County Comm GP7 SSB sets). Even with the loss of the Synchronous Detection mode, ECSS (manual SSB) continues to be work well so be it a bit finicky to make happen.

Weirdly we experienced a bug when selecting different bandwidhts in SSB mode, we had to slightly touch up the BFO setting (it moved say 25 to 50 hz). Not that this is anything disconcerting, but for the record.

Audio quality remains as it was with beta V2.0 firmware. But it seems to have a bit less audio hiss to our ears which was a plus.
The warble issue still remains as covered in the main review above.    

Band Scanner / Spectrum Display

Another very useful feature added to this 4.0 firmware is spectrum display. Mind you this is NOT in real time, but gives you a visual view of it's scanning output (yes the ATS-25 has band scanning features). It will continue to scan (audio muted) until you either back out of the mode OR when you move the tuning knob and at that point the scanning stops (audio becomes un-muted then) and then you can tune around with the knob or hit the touch the screen to tune to that part of the screen. Works in all modes too including SSB. We felt this is a very useful and fun feature added to the receiver.

ATS25 "Firmware 4.0" Band Scanner / Spectrum Display. (N9EWO Photo)

Additional FMBC Bandwidths / 10 kHz Tuning Step

As we made comment to in the main review above, LW / MW and SW bandwidths appear / sound wider than what is actually displayed (I would say about double), SSB mode bandwidths appear to be correctly displayed. Bandwidths provided are the same here as with beta V2.0 firmware (no changes).

However with FM Broadcast band there are additional bandwidths that were added. These also APPEAR to be a bit wider than what is displayed ? In any event are most useful to have these additional bandwidths available. Additionally a 10 Khz tuning step was added from the Beta V2.0 firmware for the FM Broadcast band.

FM Broadcast Bandwidths (Firmware 4.0) :
- 40, 60, 84, 110 khz (plus AUTO whatever that is and means, unknown)
FM Broadcast Tuning Steps :
- 100 and 10 KHz (10 KHz step added)

New Screen Saver Feature

A new screen saver feature was included in the 4.0 firmware. After a selectable time of 2, 5, 10 or 30 minutes the screen saver is activated (see photo below). It dances around the screen with the tuned frequency and battery indicator (if toggled on). As soon as you move the knob or touch the screen, normal operations are restored. This of course can be turned off in the main menu.

Firmware 4.0 / 4.1 Screen Saver Feature (N9EWO Photo)

Most Worthy Firmware Upgrade / Makes it a Much More Desirable "Cheapie" Receiver

Bernard has done a most excellent job with Firmware 4.0. Not that it turns a low cost portable into tabletop communications receiver (it doesn't), but in some respects performs better and is more FUN over other portable receivers in and near the same price range (and even above). Much less SSB clipping distortion for one ! Near no more chuffing for another with this firmware upgrade. It is very sensitive when connected to proper antennas. We can hope for more improvements down the road.

We need to stress again the fair construction and quality control with the "project" ATS-25 (ATS25) receiver. As is the case with most of the Chinese manufactured radio products, DOA dud (or semi-dud) rates are high and not so easy to make returns in many cases. So obtaining a properly operating sample can be a extremely frustrating crap shoot ! Also watch out for the reverse encoder wiring that suffers many of them (see the main review above).

Dave N9EWO
N9EWO, all rights reserved
ver 3.0

N9EWO Review :
ATS-25 / ATS25 / ATS25+
LW / MW / SW / FM DSP Receiver
with Bernard Binns 4.11 Firmware
HUGE "Thank You" to Dean B. as without his help, this review would NOT be here.

Bernard Binns improved version 4.11 firmware for the ATS-25.
More featured version of the 4.0 firmware that also includes double sideband synchronous detection.
Also a Wi-Fi function (not tested) and neat looking retro looking S-meter.
This firmware is a PAID upgrade that requires on-line registration / activation key.  
(N9EWO Photo)

IMPORTANT UPDATE "PLEASE READ" : We were unable to make the later version 4.12 to work properly with our OLDER ATS-25 test sample (constant power on / off resets). The author also changed the way of doing updates slightly starting with 4.12 and we were unable to do any additional testing.

Also as of updating this text, was no way to purchase this upgraded firmware (key) with the author being in Russia. If you wish to know the latest with this project , please see the web site here.

We thank Bernard for allowing us to test this advanced versions of his firmware. So the version 4.11 review information below is for archive purposes only as the older firmware versions are not available for download (even if the key has become available for purchase as you read this). Dave N9EWO

Firmware Versions Tested :  4.10 , 4.11 (Bernard Binns from Russia)

NOTE : We did not test any versions above 4.11.

Test Antenna's :
Comet DS150S Discone Antenna (30 ft height)
RF Systems MLBA-MK2 long wire (55 ft length - 24 ft height at peak)
Comet H-422 Dipole (24 ft height - Straight Configuration)

N9EWO's "ATS25" DSP Receiver Review with the Bernard Binns 4.10 / 4.11 firmware.
Antonino Russo (IU4ALH) had a huge part in improving the RDS function in this firmware version.

As compared to later version V2.0 Beta and 4.0 firmware as tested above.

- Much easier way to update firmware file to receiver.
- Double sideband Synchronous Detection (added back from V2.0 beta).
- Adjustable squelch (see con)
- Wi-Fi function added.
- 200 kHz FM Broadcast step added.
- Memory channels now unlimited (and entry bugs now fixed).
- FM broadcast RDS (Radio Data Service) display much improved, also adding time (12 or 24 hour format), and date display.
- Two S-Meter GUI choices (same 4.0 bar type and new retro analog meter style).
- New CB channel / frequency GUI.
- New propagation indicator (when Wi-Fi is on, not tested / see text)
- Many of the original version 4.0 bugs now fixed with 4.11.

Synchronous Detection looses lock on certain MW and SW signals (see text).
- Squelch does not function on SSB or Sync modes.
- Squelch sensitivity lacking (takes a fairly strong signal to activate even at one bar setting, see text)

- When Wi-Fi is on interference into audio.
- Turning OFF Wi-Fi totally required a power cycle (see text)

Easier Way To Update Firmware - Whew !

Bernard has configured the version 4.10 / 4.11 firmware to use a single bin file along with the
with the "ESP32 Download Tool" that makes updating a breeze. We first tried the version 3.9.2 of this tool and would not work with a Windows 7 laptop computer. But then attempted a earlier 3.6.3 version that did the trick. Mind you it's still a bit daunting for non computer techie folks, but is not so bad when compared to do it the raw arudino way (see photo below). IMPORTANT NOTE : CH341 USB driver is required to be installed beforehand.

The correct lone file is marked as : "SI4735_TFT_320x240_Crystal" in the file name. If for some reason you mess it up, not to worry...just redo it (radio will just not operate).

Hardest part once the firmware is installed is the "on line" multi-step activation process. It took us a couple of attempts to get it right. Slow down - take your time / don't be in a hurry. Once this is done you will not have to redo it with any new firmware updates down the road (unless you clear that in the Menu).

 The ESP32 download tool makes for MUCH eaisier firmware updates.
 However still could make non-computer folks a bit confused.
Be sure and click on ESP32 download selection when launched.
When "Finish" is seen in the lower left green block, click STOP and exit the program.
Recycle the power after. Holding the encoder knob in at power up will usually fix any display bugs. 
 We used version 3.6.3 with Windows 7 (see text). Click on photo for larger view. (N9EWO Photo edit)

Synchronous Detector Returns / Useful But Looses Lock With Test Sample

Good news is we have double sideband Synchronous Detection back as with the V2.0 beta.

The not so great news is with our test sample, it looses lock (and sometimes badly) on even very strong signals. However it still enhances audio recovery greatly and with weaker signals where the unlocking is not a problem and or so noticeable. So even with it's bug-a-boos it's still very useful. As with SSB modes the maximum bandwidth with in any sync mode is 4 kHz (just as with SSB modes), and Bernard tells us that this is a limitation of the si473x chip.

This unlock bug will vary with any given signal. It's a variable thing, you just have to try it. Many times it locks just fine and is solid. Alternative is to use the excellent ECSS  preformance (zero beat in USB or LSB modes using the BFO adjustment) and that works extremely well for a receiver in this price point.

Just try ECSS with most Tecsun receivers that have SSB modes (and a real "clipping audio distortion" stinker it is). ECSS is a aural treat with the 4.11 firmware in the ATS-25. Works very well indeed, and again at this price point is rare.

 N9EWO MP3 Audio Recording :
ATS-25  "SYNC Mode " with Binn's 4.10 / 4.11 Firmware

Here is off air 24 second MP3 audio file as made from our test sample ATS-25 with the Binns 4.1 firmware installed while receiving a strong SW broadcast station in the SYNC mode. Radio Marti via Greenville NC USA in the 25 meter band.

As you can hear it's loosing lock pretty bad. However it's a variable thing in our testing. Many times the "double sideband" SYNC mode works just fine. You just have to try it and see how it goes with any given signal. You might say ..."well it may have been slightly off frequency". No.....that possibility was tested and ruled out. Gut feeling this is effected by how deep the fading is of a signal ?

What's With The Green Digits on Sync and SSB Modes ?

With firmware 4.10 / 4.11 we see "greenish" frequency digits along with white ones while tuning in the SSB and Sync modes. Here is Bernard's explanation on this (I don't quite understand totally it either) :

"When configured in SSB modes, the frequency indicator is white when the displayed frequency is set in the si473x chip, if the color is green, it means that the frequency in si473x differs from the displayed one, while a BFO generator is used for fine tuning. If you click on the frequency on the left, the si4735 will set the  current frequency without using a BFO generator and the frequency color will change to white.The BFO generator is used in steps from -16 kHz to 16 kHz so that in SSB modes there are no claps when tuning."

New Wi-Fi Mode / Propagation Indicator / Interference Issue - ON~OFF Bug

Wi-Fi operation was a surprise to see. While not tested, I did verify that it's emits RF output here with it's SSID signal (as "H-Radio") and was able to connect to it just fine. However it was not very strong. There is a propagation indicator feature when the Wi-Fi is connected. That is a "Green-Yellow-Red" asterisk on the far left end of the frequency readout when tuning within the Ham band presets. Will give Bernard's explanation on Wi-Fi operation. :

"Wi-Fi in the receiver can be used to connect to your router, then you need to select it from the list of access points. Or to connect your phone or laptop to the receiver as an access point.If your receiver is connected to the Internet to your router, it will receive information about the current time for the city you selected (when adding a city, you must correctly specify its time zone), as well as information about the passage of radio waves. This information is displayed in various modes. For example, the color (green, yellow or red) on the main screens to the left of the frequency for the selected range. The clock is displayed in FM mode. You can also see it in INFO or RETRO. When the Wi-Fi API is ready, it will be possible to manage files inside the receiver via Wi-Fi. And the built-in H-RADIO access point will allow you to do this even in the forest, where there is no router."

Bernard Binns "4.11" ATS-25 Firmware
 SWBC Preset "BAND" Edges
In KHz
120 MB - 2300 to 2495
  90 MB - 3200 to 3400
  75 MB - 3900 to 4000
  60 MB - 4750 to 5060
  49 MB - 5900 to 6200
  41 MB - 7200 to 7600
  31 MB - 9400 to 9900
  25 MB - 11600 to 12200
  22 MB - 13570 to 13870
  19 MB - 15100 to 15800
  16 MB - 17480 to 17900
  15 MB - 18300 to 19020
  13 MB - 21450 to 21850
  11 MB - 25600 to 26100

LW - 153 to 279
MW (ITU setting 1) 530 to 1700
FM (ITU setting 1) 87.9 to 108.00 MHz
MODE button wail only allow access to AM or AM SYNC within band preset ranges shown above.
To allow USB and LSB (ECSS) in these preset broadcast ranges, hit BAND and then SW / LO button.
Now hit MODE again and the normal mode screen will then be active.
Outside these ranges the normal MODE screen will appear right away.
See this "You Tube" video for a demonstration.
PLEASE NOTE : This is also valid for firmware 4.0 FREE version.

When the Wi-Fi is switched on we detected a pulsing type of interference that irked into test sample audio amplifier (have a listen to this MP3 audio file made from the ATS-25 test sample). This was most noticeable with strong MW / SW broadcast stations with quiet audio. Even when shutting it off via the front panel icon AND all Wi-Fi selections OFF in the Menu's, it still did NOT shut it off. The ONLY way we found to completely terminate it's operation once switched on was to power off all Wi-Fi selections (main screen and menu's) and THEN cycle the power (turn it off and back on again).

Operation Except SSB Modes

There is a adjustable squelch with the 4.11 version. It is adjusted on the same volume control screen. However it is of only of real use with strong signals and does not work in SSB modes. The squelch sensitivity / adjustment range does not allow it for used with medium to lower to medium strength signals. It still can be useful mind you, but is limited. Bernard tell us that this is due to a limitation of the si473x chip.

Unlimited Memory Channels with Now Usable Alpha Tags / SSB Memory Entries - Alpha Tags are now OK

Entering the memory channel tags with the first version of 4.0 was extremely frustrating and not worth the bother with it's next charterer advance issue bug. Good news is that this bug has been completely fixed with 4.11.

Also another bug with memory entries being off has been fixed that we experienced in testing of firmware 4.0. That is memory channel entries intermittently being skewed 16 kHz LOWER than shown on main frequency display. This is also no longer an issue.

The number of memory channels is now unlimited (well at least no user is ever going to reach a limit).

RDS Display MUCH Improved / Now with Clock / Date Display

Not only is the RDS display line at a much easier color and set up better in the GUI , but the line length is at a much improved length. Also now have a RDS clock and date display on FM. For this to set one needs to find a local FM station that supports RDS time (not all do). One can also select either 12 hour or 24 hour format in the SETUP menu.

User Defined 4.10 / 4.11 "Menu" Selections
(subject to change)

- ITU Region (1, 2 or 3)
- FM band start at 64 MHz (or at 87.9 MHz)
- Save step individual for band
- Frequency digit backlight
- 24-hour time format (for RDS)

- Screen saver
- Display light off in screen saver
- Wait time to saver minutes (2, 5 ,10 and 30)
- Screen orientation 

- Minimum scale
- Maximum scale
- Auto scale
- Scan accuracy

- View not city linked
- View all city linked
- View only from current band

HARDWARE ( * -  Only if hardware supported)
- * Battery indicator
- * Charge battery show
- * Beeper on
- Wireless on
- Access point mode
- Select AP
- Internet Access Watchdog timer
- Reset to factory default
- Release license key (WARNING : Removes license key)

Additional FMBC 200 kHz Tuning Step Added

200 kHz tuning step was added from 4.0 firmware for the FM Broadcast band.

FM Broadcast Tuning Steps :
- 10, 100 and 200 kHz (200 kHz step added with 4.11)

Nifty CB Channel Mode

When the CB button is pressed, we see a cool looking orange GUI that gives the "citizens band" channel number and frequency. This is selectable for various CB frequency allocations around the world by tapping the channel number. Touching the frequency display will give quick selection of AM , LSB and USB modes.

Improved Featured Firmware Upgrade

Bernard has done another excellent job with Firmware 4.10 / 4.11. It adds many features not provided with the free 4.0 version. Even if the Sync Detection has variable lock stability, it is still most useful. Overall is a most worthy upgrade for the ATS-25 for the very minimal cost involved.

Dave N9EWO
N9EWO, all rights reserved
ver 4.0

I will NOT be held responsible for any info that is listed here

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