From 9f901384deda96a7dd021923841885ec1e4f2d67 Mon Sep 17 00:00:00 2001 From: Andreas Eversberg Date: Mon, 4 Dec 2017 14:12:11 +0100 Subject: SDR: Add option to set local oscillator (LO) offset By default it is set to -1 MHz. --- docs/sdr.html | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'docs') diff --git a/docs/sdr.html b/docs/sdr.html index 03bf8e1..687a10e 100644 --- a/docs/sdr.html +++ b/docs/sdr.html @@ -77,9 +77,7 @@ In case of B-Netz, I use the following parameters: # bnetz --sdr-soapy \ --sdr-tx-gain 50 \ --sdr-rx-gain 30 \ - --sdr-bandwidth 5000000 \ --sdr-samplerate 5000000 \ - --sdr-tune-args "OFFSET=1000000" \ -s 100000 \ -k 17 @@ -89,10 +87,10 @@ In case of B-Netz, I use the following parameters: In order to change from analog sound card to SDR, you need --sdr-soapy option. In my setup I use antennas directly connected to the SDR. Being about 1-10 meters away, I use the gain as defined above. -The IF filter requires a minimum bandwidth of 5 MHz. The sample rate must be 5 MHz minimum. +The default bandwidth follows the sample rate, if not specified using --sdr-bandwidth. Higher sample rate causes more CPU, RAM and USB load. -The local oscillator frequency causes the transmitted signal to be noisy, so I shift it 1 MHz away, using an offset. +The local oscillator frequency causes the transmitted signal to be noisy, so I shift it 1 MHz away, using the default --sdr-lo-offset. The audio processing rate of 100 KHz (-s 100000) is used to generate two channels: 17 and 19. Note that channel 19 is not given here, but will be used automatically. With B-Netz, the transmitter switches from any voice channel to the paging channel (19) whenever the phone gets paged. @@ -174,9 +172,7 @@ Because C-Netz uses only odd channel numbers for 10 KHz spacing, we use channel # cnetz --sdr-soapy \ --sdr-rx-gain 50 \ --sdr-tx-gain 30 \ - --sdr-bandwidth 5000000 \ --sdr-samplerate 5000000 \ - --sdr-tune-args "OFFSET=1000000" \ -s 100000 \ -k 131 -k 135 \ -C 0,0 @@ -192,7 +188,7 @@ Give PAL 'FUBK' test image on TV channel 21. # osmotv --sdr-soapy \ --sdr-tx-gain 60 \ - --sdr-tune-args "OFFSET=-3000000" \ + --sdr-bandwidth 60000000 \ -r 13750000 \ -c 21 \ tx-fubk -- cgit v1.2.3