I really like the JPS NIR-12 audio DSP (NIR-12 photo). The first thing you notice is that it is heavy and really well built. The cabinet appears strong enough to drive a car over, without causing any problems. It also seems to double as a big heat sink. This unit does put out a fair amount of heat. The user manual states that a 1 amp supply is needed (12 VDC) and they are not kidding. I tried a smaller supply and the output was extremely distorted. The replacement DC power connectors are available from Radio Shack, which makes it easy to move the unit. (I always have extra power cords for the equipment that is used during Field Day, VHF rover contesting , etc.)
The front panel provides for easy user control. The frequency and bandwidth adjustments are continuously variable via potentiometers. Likewise, the noise reduction and volume are also controled the same way. Engaging the notch filter is a no-brainer operation, just push the button and the birdies go away. A push button also engages the dynamic peaking function, which is yet another method of reducing white/pink atmospheric noise. The noise reduction and dynamic peaking modes can be used together.
The unit provides for DSP bypassing by applying a ground to a rear panel phono jack (high impedance). This is almost mandatory for monitoring your CW sidetone during transmit. Likewise, if you should happen to have an RFI problem, this is an easy way to take the unit "off line" during transmit. You can configure the input for either speaker or line level audio signals. A ground lug is also supplied for easy connection to your shack ground.
NIR-12 Dislikes
The headphone jack is on the rear panel. Do they think I sit behind it when I use it? The jack is a 1/4" type, and will support stereo headphones. Most of my radios have 1/8" headphone jacks, which means an adapter is needed. Since I have to use an adapter, I guess it is better to have it on the rear panel.
DSP Blaster version 2.0 has a number of new features. The developer has done a nice job of updating his software DSP. He has added quite a bit to version 2. In fact, he has had 11 updates (as of Feb. 15, '98) to version 2 since it's release back in mid-1997. He has implemented stereo output, which he uses with his coherent band pass filtering to improve signal performance. He has also beefed up some of the filters and made them tunable. The automatic frequency tracking, used during CW reception, now tracks twice as quickly. He has worked on the AGC routines, and added a squelch function, which seems to work pretty well.
During my first review of this software DSP, I had quite a bit of trouble using it while running Windows '95. Specifically, it would really bog down when I pushed it to the background and would not function properly. Since that review, I got a new PC. The old Pentium 75 Mhz was replaced by a Pentium Pro 150 Mhz. Using this new setup has greatly improved the performance of the software while running as a background process. I can now use my Windows based logging software, etc. and still have reliable signal processing. Note that this is quite a significant level of CPU processing power. You will need a fast PC in order to run this software in the background with Windows 3.1 or Windows '95. You should also note that DSP Blaster will not run with Windows NT. Those of you running NT probably already know that software running on that operating system (OS) does not get to directly play with the hardware. That is a big no-no!
If you do a lot of CW work, I think you will be quite pleased with the improvements made in version 2. I find them to be less beneficial to my SSB operation, but that is OK. There were several less significant changes that helped SSB along also.
I still recommend this program to those who meet its OS/CPU requirements.
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