PSK – 31

By Bob Wexelbaum, W2ILP

 

January 2006                              VOL.  79, NO. 1                                                   CIR 120

 
After lecturing about RTTY at the GARC, your editor continued the digital mode series by lecturing about PSK-31.  For those who want to get updated on Psk-31 or have missed my lecture, I continue here and include new features of the recent software..

 

PSK-31 is a computer keyboard mode that can be operated with the same PC to HF transceiver interface connections that were described last month for the RTTY Mode.  The only remaining requirement is that free software for PSK-31 be down loaded to the PC..

Although PSK-31 is relatively new, it has become more popular than RTTY and other keyboard modes.  There is good reason for its success.  It takes up less bandwidth than RTTY, and it is easy to automatically tune.  The type of PSK-31 that is most popular is actually BPSK-31 which means Binary Phase Shift Keying, using a bandwidth of only 31 Hertz., capable of about 50 wpm.  It is actually 31.25 but “31” for short. There is also a QPSK-31 mode which means Quadrature Phase Shift Keying. In BPSK, which is most popular, only two phases are used:0 degrees and 180 degrees..  In QPSK four phases are used 0, 90, 180, and 270 degrees. 

 PSK-31 was invented by Peter Martinez, G3PLX.  He invented a code for it, which is called  Varicode.  Unlike Bardot or ASCII, this code does not have a fixed number of bits for all characters.  Like Morse code, the number of bits varies depending on how frequently characters are used.  In Morse code “E” is represented by one dit, while “Z” is Dah Dah dit dit (four sounds). In Varicode “E” is 11 (2 bits), and “Z” is 111010101 (9 bits).  Morse Operators recognize the spaces between parts of characters, between characters and between words.  For RTTY there must be start and stop pulses to signify spaces.  Varicode is so arranged that there is no character that uses “00” as part of its code. Thus “00” can be used for spacing between characters.  Because the 180 degree phase shift is easily recognized it can be recognized in noise at very low signal levels and it can beat RTTY and have similar or better advantages over CW, provided that the signal does not phase distort.  The problem of phase distortion only seems to exist when signals take a great circle route over polar regions, but even then it may not bother BPSK-31, as it is only a temporary flutter phenomena at most times.  The software for PSK-31 may be found at:-   http://www.pavane.net/digipan/digipan.htm  

This software works with Windows 95 and more recent PC operating systems.  There is also other PSK-31 software available for Macs and for Linux operating systems.

The software for PCs is called DigiPan, which means Digital Panoramic Tuning.  There exists other PC software for PSK-31.  Originally software called MIXW32 was considered to be better by some hams, but revisions of the original DigiPan have now made it the preferred software.  Original versions only permitted reading two PSK-31 signal texts at the same time.  The latest version DigiPan 2.0 allows you to monitor up to 24 signal texts at the same time and to automatically tune for transmitting to any one that you want to work.  The signal texts show up simultaneously on your display screen on 24 horizontal lines from up to 24 different signals.  DigiPan is the product of programming by Ship Teller, KH6TY, with the help of Nick Fedoseev, UT2UZ.

When you use an HF transceiver in the SSB mode you have a receiver RF bandpass of somewhere between 2 and 3 kHz, depending on the transceiver’s filtering.  Typically it is flat at about 2.4 kHz.  It is theoretically possible to receive as many as 40 PSK-31 signals in that bandpass, at the same time. Each PSK-31 RF signal will produce a different audio frequency signal.  The audio signals are all there at the same time and need not be scanned to in order to read them, as the PC sound card continuously separates, decodes and converts to ASCII each audio signal within the transceiver’s bandpass at the same time.  To QSO with any one of the signals whose text you copy, you can slew to it using your PC’s mouse and you will be transmitting on the same RF frequency by duplicating the same tone when you modulate your transceiver with.  The signal you select will have its text show up on the left side of the display, where the text of your transmit signal will also appear.  

PSK-31 is a very new mode.  The first version of DigiPan was released on January 4, 2000, only six years ago.  The Version that you now can download is the ninth release of November 11, 2004, which added multichannel reception, CQ alert, Internet call sign lookup, and Rx and Tx offset adjustments.   

A Panoramic acquisition display is actually a graph which has frequency as its horizontal scale and time as its vertical scale.  When the RF gain of the transceiver is set so that the background noise level is audible the display looks like a waterfall, slowly moving down as a function of time, and that is what it is called.  A short coming of the panoramic method is that the strongest signal received within the SSB bandpass will control the transceiver’s AGC.  It may thus attenuate weaker signals that are being received at the same time as the strong one.  This may interrupt your QSO with a weak signal and be difficult or impossible to do much about unless your transceiver can quickly provide for the selection of a narrower bandpass filter, without losing the desired signal.

            Operating PSK-31 is no different than RTTY, in that you can find a clear frequency area on the waterfall (panoramic display) and mark that frequency with an arrow that is controlled by your PC’s mouse and call CQ there. You can also simultaneously monitor up to 24 active signals and when you see that a ham has ended a QSO with another ham, you can call him or her by moving the arrow to his or her tracked frequency.  Calling CQ or QRZ or responding to a CQ is usually accomplished by only clicking on to one of the assigned buttons on the display. The software can automatically insert the call sign of a received station that is calling CQ, and CQ calling texts are highlighted in color.  Just clicking on the text or call sign of a receive station automatically transfers it to the active Rx message area for a QSO.  It may take some time to get used to the advantages offered by these features and to also use the optional automatic logging functions that the software provides.  Manual tuning of the transceiver has been eliminated by point and click mouse tuning.  This no longer requires very fine tuning resolution by the receiver’s local oscillator, but it does require good L.O. temperature stability.

             When you set up for any of the keyboard modes you can enter your call sign, your handle, the types of equipment you use, etc.  Additional files can be “canned “(stored in the PC), so that there is no need to retype what are known as “brag files” to each new contact.  Once done, you will never need to type this information again, as you can transmit it automatically by clicking on what are called macro buttons on your display.  Other than the basic information, unique messages and casual rag chewing paragraphs can be transmitted by typing them out.  You can use all of the common abbreviations that hams use on CW.

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                                                         PSK-31 (continued)

 

             Use “Q” code whenever practical, especially for sending signal reports.  Since all of the hams who use keyboard modes are computer savvy, it is common practice to refer hams to QRZ or Buckmaster, so that they may pick up details about you such as grid location, postal address, e-mail address, class of license and your biography (bio).  IMHO all hams should provide some biographical information about themselves on the QRZ site.  It is also possible to insert a photo of yourself there.

            BPSK-31 sends digital ones uninverted and digital zeros as inverted (by 180 degrees) wave forms.  The phase differences are detected by comparing the received signal to an uninverted reference which becomes developed automatically as a function of the synchronizing process.  Received signals get initially synchronized soon after reception, even when reception begins in the middle of a message, because of the unique coding for spaces..  PSK signals appear on the waterfall display as single traces that are thick enough to look sometwhat like tiny railroad tracks.  They are easy to identify from broken CW signals, two track RTTY signals or MFSK multi-track signals.  It is possible for PC sound cards to detect, decode and work weak PSK signals that have ghostlike tracks and can not even be heard as audible tones.  Like RTTY, PSK transmitions have 100% duty cycles as the carrier is always on when transmitting in one phase or the other.

            The amplitude of the modulating audio signal going to the transceiver is critical.  The proper amplitude will achieve a proper Intermodulation Distortion (IMD) level. You can not accurately measure the IMD of your Tx signal yourself even if you have access to another receiver, but the software enables you to measure the IMD level of signals that you receive.  Therefore you must ask a station that you QSO with to give you your IMD reading.  This has to be a station who is not too weak and not too strong for best results..  As explained for RTTY, the modulating amplitude may be controlled by a potentiometer in the line to the transceiver or by software adjustment.   As you make adjustment of your modulation you may have to ask the receiving ham to let you know if improvement is made several times.   The transmitter should be modulated in the most linear manner possible.  A proper modulating amplitude will result in an IMD reading of -25 dB or less.  An IMD reading of -20 db is bad and could result in visible undesired sidebands.

            BPSK-31 was first popular on 20-Meters clustered around 14.070 MHz.  There is now BPSK operation on all of the HF ham bands, and some on 6 and 2 Meter VHF.  QPSK works well for short range VHF, where there is seldom any phase distortion problems. Under some difficult band conditions QPSK may work better than BPSK on HF and some operators switch to QPSK to try for an improvement.  QPSK requires that the SSB transceiver be switched to upper sideband which is the usual standard.  Either sideband could work if both receiving and sending station use the same sideband.   Either sideband can be used for BPSK as the 180 degree phase shift does not involve phasor directivity.

            PSK63 is another new mode that is actually the same as PSK31, except for running at a speed that enables 100 wpm transmission.  It only requires a bandwidth of 63 Hz.  Since very few of us if any can type at 100 wpm, why use PSK63?  The answer is that you can take advantage of the higher speed in contests where you don’t rag chew and all of the contest information that is required can be stored and sent automatically.  It is also practical to send color thumbnail portraits in less than 2 minute each using PSK63.  The same site where you can download PSK31 can give you PSK63. It also tells of a PSK63 DXCC contest.  On 20-Meters PSK63 is to be used between 14072.5 and 14080.0 kHz.  It is to be used 2.5 KHz higher than PSK31 on the other bands.  Although sub band plans may still be legally optional, PSK users want the PACTOR users to stay off their frequencies.  PACTOR, another keyboard mode is not as popular as the PSK modes because it requires a propriety manufactured TNC. The DigiPan software allows you to receive PACTOR for the purpose of identifying the PACTOR stations by their call signs, even when they don’t use any CW identification.  

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PRESIDENT’S PAGE

BY

KE2LJ

 

           

      

Last month’s meeting was not really a formal assembly of the membership. We had our Club Holiday at the same place as last year, the Country Buffet. Because of the traffic, and other commitments, our people roll in whenever they can get there.  I arrived after work, at 5:30 and stayed until the last person left around 7. The fun part is not really all the eating I can do, but meeting the members that we don’t normally see during the rest of the year. Some of the guys come from pretty far out East, and I applaud the effort they make to get there.

 On Sunday 1/8, many of us attended Ham Radio University at Briarcliff College in Bethpage. You may know the building as Plant 35. It now has dozens of classrooms on the first floor. HRU is not a flea market, but a series of seminars on aspects of Hamming, including ARES, digital modes, etc. You can see the list of forums on the net at the HRU website. Many of us GARC people are also in LIDXA, and we did 2 hour lecture on various DX topics. It was fun for us to do, but somewhat under attended. But it’s a good way to try to get other people involved. There are way too many Hams that are totally withdrawn from the Hobby, and we really would like for them to get interested again.

 One of the jobs of the President is to make sure the monthly meetings occur. The purpose for a meeting is two-fold. We want to present something educational, and we want the attendees to be entertained as well. We have been doing this at GARC for decades, and it gets tougher all the time. There are very few speakers available that can come to a Club meeting and speak nicely on an aspect of radio or computers. We have pretty much used all that we can. I have even checked the ARRL’s list of speakers, and there isn’t anybody we can get. That doesn’t leave us too many options. One is to have the members do a little talk, and we certainly have done that quite often. Another option is to widen the scope of acceptable topics, and not limit the subjects to radio or computers. This is where we are now. I mentioned last month that many of our Club Hams also have other hobbies. I encourage them to talk to us about these outside activities, but we have no takers yet. That places the burden on me a little more than it should be. So, for now, I am going to entertain the membership with slide shows of some of the things I am involved in, that don’t relate to Ham Radio. There are two main things that occupy my time these days. One is railroading, and the other is exploring the Long Island Motor Parkway (LIMP). On the first subject, I have made three expeditions to museum type railroads since October. The first was to a place called Gulf Coast RR Museum near my new house in Tampa. I did some Engineering there, pulling a small train on three trips over their 6 miles of private track. In November, my Son Michael and I took the half-day Steam Locomotive class in Essex Ct. which features a one hour session with each guy actually running that 1928 Alco Steamer for an hour. Finally, on 12/24, Michael and I were at the Gold Coast RR Museum near Miami where we actually had a whole train yard to ourselves for the day. We started up, operated, and shutdown four different Diesel locos there. We made up some long trains, and pulled them in, and out, of the yard. We actually hooked up air hoses and couplers. We operated switch tracks, and moved rail cars around the yard for quite a few hours. It was a tremendous experience, and we had a ton of fun. I took lots of pictures on these last two operations, and I will be presenting these at the January meeting. So, instead of talking about radio or computers this time, I’ll be talking about my railroading experiences. If you have any interest in trains at all, I think you will find this quite amazing. In future sessions, I’ll be speaking on the work we have been doing to rediscover the LIMP. Last week we were at the Old Bethpage Restoration site, and we uncovered the right-of-way for almost a mile, right up to the eastern boundary of Nassau County. One of the 2 remaining bridges is in the woods there, and I took lots of pictures. I think you will find this fascinating, also.

CQ DE WA2LQO DECEMBER 2005

GRUMMAN AMATEUR RADIO CLUB

MINUTES OF GENERAL MEETING -12/21/2005

Karen KC2OPX

This meeting was actually the Holiday Party, held at the Old Country Buffet of Levittown.

          Because the meeting was actually a party, no formal minutes were taken. The following comes from the minutes of the board meeting of 12/14/05.

 

TREASURERS REPORT – Ed, WB2EAV          REPEATERS – Gordon, KB2UB

 Finances continue to be in good shape.                    Nothing new to report.

                                                                                                                                                                                                                                 

VE REPORT – Bob, W2ILP                                  NET REPORT- Zack, WB2PUE

One applicant passed  the Technician exam..            Sunday morning 40-Meter propagation was poor.

VEs present were AG2A, KC2HNN, N2SFT           Thursday night 2-Meter net was good.

and W2ILP.                                                                                                                                                                                                                                                                                                      .

2006  G. A. R. C. DUES

Dues for 2006 are now due.  You are paid up through the end of the year shown on your address                    label.

Basic membership dues are $20 per year.  Multiple members in the same household pay the family rate of $30.  Retirees living outside of the New York City metropolitan area can pay the associate  member rate of $5.

Send dues checks, payable to GARC (or any other mail) to:

GARC

P.O. Box 644

Bethpage, NY 11714

                  

GARC NETS:

40 Meters: 7.289 MHz at 7:30 AM EST Sundays.

20 Meters: The 20 Meter WAG net has been cancelled because of inactivity.

2 Meters (via repeaters): 146.745 MHz  (-.600)at 8:30 PM EST Thursdays.

                                           145.330 MHz (- .600) at 9:00 PM EST Thursdays.

[Tone for both repeaters is 136.5 Hz]         (ARES/RACES) Mondays

                                                                                                    

MEETINGS

General Meetings of the GARC are held on the third Wednesday of each month, starting at 5:30 PM.   The meetings are usually held at the Underwriters Lab, 1285 Walt Whitman Road,  Melville, NY.  Driving directions and maps can be obtained from http://www.mapquest.com   It is suggested that the GARC Web Site be checked to be certain of meeting location, which may change after this newsletter is distributed. Board meetings are held eight days before the General Meeting and GARC members are invited. to attend, but please call Pat Masterson, KE2LJ, at 516-346-7125 to confirm place and time of meeting.

                                                          

GARC WEB SITE

The web site of the GARC can be found at http://www.qsl.net/wa2lqo/     Webmaster is Pat Masterson KE2LJ.  Pictures of GARC activities, archives of newsletters, roster of members, and other information about the GARC may be found there.                                                                                                         Page 5

                                                                                                                                                                                                                                                                                                                                                                                                               

Internet Link of the Month for Internerds by W2ILP

 

I previously told you about Dimension 4, which is software that can accurately update your computer clock.  You can see the result on your lower right tool bar.  When the computer actually runs the program you can slew your mouse over an icon on the tool bar and find out if your computer time has been corrected, when, and by how much.   You can’t do anything about the real time itself or stop time from marching on.  Another thing you can not change is the weather.  As Mark Twain said, “Everyone talks about the weather but nobody can do anything about it”.  For lack of anything to rag chew about that is non-political and non-controversial, it is always safe to tell hams, who you are in a QSO with, what the weather at your QTH is like and ask how the weather is at their QTH, even if you could care less.  To do a good job of weather condition detecting you would need an outside thermometer, a barometer, an anemometer, etc. You don’t need anything but your PC, ISP and software called WeatherBug.  With WeatherBug on your hard drive, you don’t need to own any weather instrumentation.  Just down load:  http://www.weatherbug.com

You will be prompted to type in your postal zip code, which serves to id your immediate neighborhood.

I am not sure if WeatherBug is available everywhere in the U.S.  I suggest that you try and see if your zip code works.  Where WeatherBug works you will get a numeric readout of your outside temperature to the nearest degree on the toolbar where the time is.  Clicking on the tool bar temperature will bring up a window that will show the temperature to the nearest tenth of a degree, wind direction, wind speed, barometric pressure and other weather information as well as the source of the information.  Mine, here in Commack, comes from nearby Suffolk Community College.  On week ends and holidays it comes from churches or schools in the Commack area.  Another feature is weather alerts.  You get alerted by a cricket sound if your audio is turned on when an alert is predicted.  You can then click on the temperature icon and find out the nature of the predicted alert for your area if you want to know.  Since storms and flood conditions are cause for most alerts it might be a good idea to pay attention to them.  Now here is the down side.  WeatherBug is free but you can pay to subscribe to it if you want it to be commercial free.  I don’t pay.  The commercials are from targeted local merchants as well as national businesses.  They are not independent pop-ups but appear on the same window with the WX information.  They don’t bother me much. There is also another feature that you might like.  It enables you to optionally look at a lot of outdoor photos, which might be of interest but can be ignored.  Like most stuff on your home page, WeatherBug adds a little time to the booting up process. In my opinion it is worth it.  I know that some may prefer to just monitor the marine weather forecasts on VHF radio.  Whatever floats your boat or flops your mop is best for you.  I like the idea of having it all on the tool bar.

 

PUZZLE

Here is another cryptogram:-

 

WDD  YZZX  IZZOF  WSM  WDUOM  UC  EVWE  EVMJ  WSM  ESRMS  EVWC  UA  EVMJ  VWX

 

SMWDDJ  VWQQMCMX  WCX  WAEMS  JZR  WSM  AUCUFVMX  SMWXUCY  ZCM  JZR 

 

VWQQMCMX  EZ  JZR.       – MSCMFE  VMNUCYBWJ-- 

 

 

Solution to December’s cryptogram:

A MESSAGE MAY BE SENT AROUND THE WORLD IN ONE-FIFTH OF A SECOND, YET IT MAY TAKE YEARS FOR IT TO GET FROM THE OUTSIDE OF SOMEONE”S HEAD TO THE INSIDE.

                                                                                                                                                 Page 6

 


GARC VE SESSIONS

 

We are continuing to proctor exams for all classes of ham licenses on the second Tuesday of each month starting at 5:00 PM.

 

The present exams are:

Element 1: 5 WPM CW,

Element 2: Technician,

Element 3: General and

Element 4: Amateur Extra Class.

 

The fee for 2006 is $14 for all exams taken in one sitting.  I have not received any information of any fee change this year as of the present time.

 

Applicants for upgrades should bring a photocopy of their license and their FRN number.

 

New, first time applicants should be aware that their Social Security number will be required on their application form.  All applicants should bring driver’s license or other picture ID.

 

The exams are given at the Underwriters Lab in Melville, unless otherwise noted.   This is the same building where GARC meetings are presently held.

 

For any further information e-mail: -

w2ilp@optonline.net or phone: -

(631) 499-2214

 

Study material information is available at the http://www.arrl.org or the http://www.w5yi.org web site.

All VECs use the same Q & A pools.

Since the beginning of the VE program the GARC has provided opportunities to take ham exams monthly, during all twelve months of every year.

 

Bob Wexelbaum, W2ILP

and the Grumman VE team.

                                   

 

CQ de WA2LQO

January 2006

 VOL.  79,  NO.  1

 

EDITOR

Bob Wexelbaum  W2ILP

(631) 499-2214

w2ilp@optonline.net

 

CONTRIBUTING WRITERS

PAT MASTERSON, KE2LJ

And all the members of GARC (we hope!)

 

CQ de WA2LQO is published monthly by the Grumman Amateur Radio Club for its members and friends. Send articles and amateur equipment advertisements to:

KE2LJ or W2ILP

 

ELECTRONIC SUBMISSIONS

If you want to submit articles or amateur equipment ads via e-mail do the following:

1. For submission direct to editor call him at above number to set up a transfer.

2. For e-mail transfer:

Internet Address

bat@grumman.com

 

 
EDITORIAL

 

I enjoyed the holiday party. I was glad to sit at a table with Marty Getzelman, N2CRD at the party.   Marty lives out east on L.I. and although we talked on the 5.33 WAG Net, Marty hadn’t seen me since I grew a moustache.

I trust that our holiday party was also well enjoyed by all who attended.  It was not however, a formal club meeting and official minutes could not be taken.

Our new club secretary, Karen, KC2OPX has sent me the minutes of our December board meeting and the report in this newsletter was assembled using that.

I want to again remind those who have not yet paid, that the GARC 2006 dues are now due.  Last month I said that a check should be sent to our treasurer, Ed Gallenda, WB2EAV.  This was an error.

Checks should be mailed to the GARC, P.O. Box 0644, Bethpage, NY 11714.

They should be made payable to GARC.

Just for my 2 cents and yours…If you had mailed your dues early you could have avoided a first class postage rate increase.

 

VY 73,

 

W2ILP (Idiots Lick Postage)..Not me.  I haven’t licked any stamps since pregummed ones became available.

 

GRUMMAN AMATEUR RADIO CLUB OFFICERS FOR 2005

 

President                Pat Masterson              KE2LJ            V01-01    516-346-7125

Vice President       Gordon Sammis            KB2UB          Retiree     631-666-7463

Secretary               Karen Cefalo                KC2OPX                       
Treasurer               Ed Gellender                  WB2EAV        X02-14   516-575-0013

1Yr Board Member    Zack Zilavy            WB2PUE        Retiree     631-667-4628
1YrBoard Member     Dave Ledo             AB2EF

1Yr Board Member    Bob Christen          W2FPF           

2Yr Board Member    Bob Wexelbaum     W2ILP         Retiree     631-499-2214

2Yr Board Member    Jack Cotterell         WA2PYK       Retiree     516-249-0979

Trustee WA2LQO        Ray Schubnel        W2DKM      Retiree

 

STANDING COMMITTEE CHAIRMEN

 

Meeting Programs       Contact a Board Member

FCC Exam Coord.      Bob Wexelbaum     W2ILP                          631-499-2214

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 


                           TECHNICAL BITS                

 

The Dynamic Range of a receiver is a measure of the range of signal levels, from the weakest to strongest that can be handled.  It starts with the weakest signal that can produce a standard audio output level and be above the noise floor and ends with the strongest signal which can deliver the same standard audio level without saturation or excessive distortion.  To achieve these ends, it is necessary to use some form of automatic gain control (AGC).  For an AM or FM signal, which has a constant RF carrier, it is relatively easy to, by the use of a detector diode, develop a voltage level that is proportional to the received carrier strength. The same detector that is used to convert the I.F. signal to audio may be used as the AGC detector.  This required DC coupling for AGC and AC coupling for audio.  Sometimes separate diodes are used for these two functions.  It is the AGC voltage that drives the S Meter in most radios.  Sometimes the AGC voltage must be amplified to achieve the required result.  The AGC voltage is developed so that it can be used to control the gain of the receiver’s RF and/or IF amplifiers.  Designers must take care to prevent the AGC controlling circuits from changing the loaded Qs of tuned RF or IF circuits.

This has become easier with the use of IGFETs which isolate the gain control from the amplification functions as well as vacuum tubes can.  Since CW is keyed on and off it does not have a constant carrier. SSB has its carrier nulled out and produces a sideband that varies as a function of the audio modulation.  Obviously both of these modes will cause the AGC to vary and you can see the variation on the s-Meter.

More next month.