Icom R-7000 Rcvr Panadapter
- Thread starter W2MR
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I occasionally have breakfast with some guys who have discussed panadapters. One swears by the Elecraft P3 while the other swears by LP-PAN.
The Elecraft P3 would certainly work but would be limited to 200KHz span. I believe the IF output of the R-7000 would have to be at least 6MHz wide since it was meant to be used with the TVR7000 TV adapter.
I tried a panadapter on my R-7100 and was very disappointed because the IF output is subject to AGC control of whatever signal is within the narrow passband of the receiver. As you tune across the band you can see all the signals on the panadapter but as soon as you tune one in the gain drops on the IF output and the display is rendered almost useless. I suspect the R-7000 will behave the same.
The LP-PAN is an external box that takes in the IF and outputs baseband IQ which is fed to a computer sound card. You can get up to about 200KHz of span with a 24bit/192k sample rate audio card and run the free Power SDR software similar to what runs on the Flex radios.
I ran LP-PAN on an Elecraft K3 for awhile then went with the P3 panadapter, which is a fantastic little box, especially with the option to feed an external VGA monitor.
prcguy
I tried a panadapter on my R-7100 and was very disappointed because the IF output is subject to AGC control of whatever signal is within the narrow passband of the receiver. As you tune across the band you can see all the signals on the panadapter but as soon as you tune one in the gain drops on the IF output and the display is rendered almost useless. I suspect the R-7000 will behave the same.
The LP-PAN is an external box that takes in the IF and outputs baseband IQ which is fed to a computer sound card. You can get up to about 200KHz of span with a 24bit/192k sample rate audio card and run the free Power SDR software similar to what runs on the Flex radios.
I ran LP-PAN on an Elecraft K3 for awhile then went with the P3 panadapter, which is a fantastic little box, especially with the option to feed an external VGA monitor.
prcguy
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My R7000 has a 1 dB bandwidth of roughly 21 MHz, the 3 dB bandwidth is about 22 MHz. The somewhat usable bandwidth exceeds 30 MHz. But, this is not symmetrical around the 10.7 MHz IF freq. In my case the 1 dB bandwidth starts at about 3.0 MHz and runs to 24.0 MHz. The noise floor is NOT flat across that width, in fact the noise floor is 23 dB higher at 3.0 MHz than at 10.7 MHz.
Spectrum shape of my R7000 noise floor here, note the markers showing the noise floor at 3.0, 10.7, 15.0, and 24 MHz:
Keep in mind that the noise floor in the above image is sampled for a 30 MHz bandwidth, and that results in a higher noise floor than the smaller DDC window would show. So individual signals demodulated on a more narrow band sample would show about an SNR increase.
For those that are wondering how this would impact the usability of a panadapter it means that setting a waterfall noise floor to show a low level of noise in one segment would result in either high noise (in some regions) or undetectable signals (in other regions).
The waterfall of this noise floor looks like this:
Over all I find it best to use the 10 to 22 MHz area, it has the flattest and lowest noise floor. There is nothing that says you have to use the 10.7 MHz area as center, except, of course, if you are demodulating the audio with the R7000.
SDRs make dandy panadadpters, and then you can use the SDR to demod the signal, and use whatever offset you want, getting away from the 10.7 MHz “center” of the IF.
I have used the SoftRock Ensemble II, Net-SDR, SDR-14, SDR-IQ, Perseus, QS1R, and WinRadio Excalibur as a panadapter on multiple radios here, including the R7000, R7100 (when I owned one), and the R8500.
For low cost the SoftRock Ensemble II makes a great panadapter, but you are limited to whatever bandwidth it and your sound card can do, no more than 192 kHz and often less than that.
The SDR-IQ will do 190 kHz and the SpectraVue software can also control and auto center the front-end radio using whatever offset you desire. The SDR-14 will do wider displays if you use it only to display, and up to 190 kHz if you use it to demodulate the audio.
The Net-SDR and Perseus will do up to 1.6 MHz width. The SpectraVue software is very flexible for this application, as I said above. The Perseus software will do offsets but that is a pay feature for it.
The QS1R will do up to 4 MHz of width.
The WinRadio Excalibur will do up to 50 MHz on the wideband display and still allow the DDC window to concurrently show details and demodulate in a 20 kHz to 2 MHz window, user selectable. Yes, you can see every signal for more than 25 MHz of width, all at one time, and demodulate any of them in the SDR without touching the tuning dial of the R7000 using the Excalibur for this application. Here is an example of 451.3 to 464 MHz being displayed (this image is actually the R8500 and Excalibur combination):
Hope that helps,
T!
Spectrum shape of my R7000 noise floor here, note the markers showing the noise floor at 3.0, 10.7, 15.0, and 24 MHz:
Keep in mind that the noise floor in the above image is sampled for a 30 MHz bandwidth, and that results in a higher noise floor than the smaller DDC window would show. So individual signals demodulated on a more narrow band sample would show about an SNR increase.
For those that are wondering how this would impact the usability of a panadapter it means that setting a waterfall noise floor to show a low level of noise in one segment would result in either high noise (in some regions) or undetectable signals (in other regions).
The waterfall of this noise floor looks like this:
Over all I find it best to use the 10 to 22 MHz area, it has the flattest and lowest noise floor. There is nothing that says you have to use the 10.7 MHz area as center, except, of course, if you are demodulating the audio with the R7000.
SDRs make dandy panadadpters, and then you can use the SDR to demod the signal, and use whatever offset you want, getting away from the 10.7 MHz “center” of the IF.
I have used the SoftRock Ensemble II, Net-SDR, SDR-14, SDR-IQ, Perseus, QS1R, and WinRadio Excalibur as a panadapter on multiple radios here, including the R7000, R7100 (when I owned one), and the R8500.
For low cost the SoftRock Ensemble II makes a great panadapter, but you are limited to whatever bandwidth it and your sound card can do, no more than 192 kHz and often less than that.
The SDR-IQ will do 190 kHz and the SpectraVue software can also control and auto center the front-end radio using whatever offset you desire. The SDR-14 will do wider displays if you use it only to display, and up to 190 kHz if you use it to demodulate the audio.
The Net-SDR and Perseus will do up to 1.6 MHz width. The SpectraVue software is very flexible for this application, as I said above. The Perseus software will do offsets but that is a pay feature for it.
The QS1R will do up to 4 MHz of width.
The WinRadio Excalibur will do up to 50 MHz on the wideband display and still allow the DDC window to concurrently show details and demodulate in a 20 kHz to 2 MHz window, user selectable. Yes, you can see every signal for more than 25 MHz of width, all at one time, and demodulate any of them in the SDR without touching the tuning dial of the R7000 using the Excalibur for this application. Here is an example of 451.3 to 464 MHz being displayed (this image is actually the R8500 and Excalibur combination):
Hope that helps,
T!
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