Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Andy,
To filter at RF level between 145.800 and 145.825 MHz will require a lot of cavities and even if possible most probably the attenuation would make the whole exercise useless.
May be at baseband level but I am not really competent to advise, your question is of interest and anyone who may help there is most welcome.
73
Jean Marc (3B8DU)
On Dec 28, 2020, at 9:34 PM, Andy Brian [email protected] wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
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Try attenuate RF entry level on SDR Dongle
73, lu7abf, Pedro
On 12/28/20, Jean Marc Momple [email protected] wrote:
Andy,
To filter at RF level between 145.800 and 145.825 MHz will require a lot of cavities and even if possible most probably the attenuation would make the whole exercise useless.
May be at baseband level but I am not really competent to advise, your question is of interest and anyone who may help there is most welcome.
73
Jean Marc (3B8DU)
On Dec 28, 2020, at 9:34 PM, Andy Brian [email protected] wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
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Thanks all for good suggestions. I Will try all to find a good results. I start searching for solutions because I saw so many good received from SSTV pictures from ISS this days. APRS frequency here is on 144.800MHz
BR Andy
On Mon, Dec 28, 2020 at 7:15 PM Pedro Converso [email protected] wrote:
Try attenuate RF entry level on SDR Dongle
73, lu7abf, Pedro
On 12/28/20, Jean Marc Momple [email protected] wrote:
Andy,
To filter at RF level between 145.800 and 145.825 MHz will require a lot
of
cavities and even if possible most probably the attenuation would make
the
whole exercise useless.
May be at baseband level but I am not really competent to advise, your question is of interest and anyone who may help there is most welcome.
73
Jean Marc (3B8DU)
On Dec 28, 2020, at 9:34 PM, Andy Brian [email protected] wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
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Hi Andy,
Because you have 1 MHz between two signals, then you can try to do something yourself. HAM radio is an experiment ;).
If I would be you I will try to make two quarter-wave impedance transformers using a cable, as the frequency trap. As a consequence, you can reach a different ratio between both signals on 144 and 145 MHz. Sorry for my not professional/technical English words in this case. I hope people who know technical English better than me and catch my idea can write to you more (some keywords).
Another similar solution is the notch filter from cable, eg. http://dl4xav.sysve.de/coax.filter/coax-filter.html
Here is another solution https://www.pa0nhc.nl/IMDfilter/EN/CableNotchFilter145MHz/KabelNotchFilterV1...
If the trap/notch filter will be too wide (wider than 1MHz), then you can try to move the maximum of the resonance/attenuation much more outside both frequencies 144 and 145 and you can try to operate on the slope.
73, Armand SP3QFE
W dniu 2020-12-28 19:29, Andy Brian napisał(a):
Thanks all for good suggestions. I Will try all to find a good results. I start searching for solutions because I saw so many good received from SSTV pictures from ISS this days. APRS frequency here is on 144.800MHz
BR Andy
On Mon, Dec 28, 2020 at 7:15 PM Pedro Converso [email protected] wrote:
Try attenuate RF entry level on SDR Dongle
73, lu7abf, Pedro
On 12/28/20, Jean Marc Momple [email protected] wrote:
Andy,
To filter at RF level between 145.800 and 145.825 MHz will require
a lot of
cavities and even if possible most probably the attenuation would
make the
whole exercise useless.
May be at baseband level but I am not really competent to advise,
your
question is of interest and anyone who may help there is most
welcome.
73
Jean Marc (3B8DU)
On Dec 28, 2020, at 9:34 PM, Andy Brian [email protected]
wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with
SDR#
program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines
on
pictures and I analysed that this is the case of transmission
with APRS
local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program
to
reduce the infulence from of transmitter which is far away from 145.8MHz but still in the
2MHz
bandwidth of RTL2832?
BR Andy
Sent via AMSAT-BB(a)amsat.org [1]. AMSAT-NA makes this open forum
available
to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official
views of
AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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Sent via AMSAT-BB(a)amsat.org [1]. AMSAT-NA makes this open forum
available
to all interested persons worldwide without requiring membership.
Opinions
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views of
AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
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[1] http://amsat.org
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Hi,
When you are using an SDR device, without any external hardware filters, then it doesn't matter where you listen to (your range of 2MHz). In this case, you can observe interferences also from other bands!
You wrote about the APRS from the local station 5km away, so it is the terrestrial source. What is the freqency?
You can make as narrow as possible antennas, you can use or build some RF filter between antenna and the SDR, however, I think a cheaper solution is to build some 2m handy radio, where you have some RF filters and some attenuation between nearest freqencies.
73, Armand SP3QFE
W dniu 2020-12-28 18:34, Andy Brian napisał(a):
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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Hartwig 144-149mhz LNA solved my RFI problems with my SATNOGS station.
https://network.satnogs.org/stations/984/
73 KJ6DZB cm87
On Mon, Dec 28, 2020 at 9:35 AM Andy Brian [email protected] wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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Hi,
I think that the LNA will boost both 144 and 145 MHz signals.
Armand
W dniu 2020-12-28 21:11, Mathison Ott napisał(a):
Hartwig 144-149mhz LNA solved my RFI problems with my SATNOGS station.
https://network.satnogs.org/stations/984/
73 KJ6DZB cm87
On Mon, Dec 28, 2020 at 9:35 AM Andy Brian [email protected] wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Sent via AMSAT-BB(a)amsat.org [1]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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Links:
[1] http://amsat.org
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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LNAs are good, but they also raise the noise power in the pass band, right? From my experience, too much amplification is a bad thing when seeking lower power RF signals. Why not consider better (industrial/lab quality) components at the RF front ends taking out the components supplied with the cheap dongles? Use the back end, but reengineer the front end. Those parts are probably the cheapest quality so if one could get a 0.5 or 1 dB increase .... and I learnt of a tip: older radio operators (WWII to 1960s) used tube front ends in RX boards for weak signal VHF. Amazing technology that should still be interesting. Narrow-Q but high dynamic range! Like an audio pre-amp with tube circuits.
Discussion and criticism welcome.
Samudra N3RDX
-----Original Message----- From: Armand SP3QFE [email protected] Sent: Monday, December 28, 2020 3:14 PM To: Mathison Ott [email protected] Cc: Andy Brian [email protected]; AMSAT-BB [email protected] Subject: [AMSAT-BB] Re: SSTV with SDR RTL2832
Hi,
I think that the LNA will boost both 144 and 145 MHz signals.
Armand
W dniu 2020-12-28 21:11, Mathison Ott napisał(a):
Hartwig 144-149mhz LNA solved my RFI problems with my SATNOGS station.
https://network.satnogs.org/stations/984/
73 KJ6DZB cm87
On Mon, Dec 28, 2020 at 9:35 AM Andy Brian [email protected] wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Sent via AMSAT-BB(a)amsat.org [1]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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Links:
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Watch out!
LNAs can do more harm than good for IN BAND strong signals.
El 12/28/20 a las 3:11 p. m., Mathison Ott escribió:
Hartwig 144-149mhz LNA solved my RFI problems with my SATNOGS station.
https://network.satnogs.org/stations/984/
73 KJ6DZB cm87
On Mon, Dec 28, 2020 at 9:35 AM Andy Brian <[email protected] mailto:[email protected]> wrote:
Hi, I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832? BR Andy ----------------------------------------------------------- Sent via AMSAT-BB(a)amsat.org <http://amsat.org>. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/[email protected] To unsubscribe send an email to amsat-bb-leave(a)amsat.org <http://amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
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Hi Brian,
If you can, then enable decimation and if that isn't possible lower the sample rate.
Further give the following plugins a try, Audio Processor and IF Processor both can be found on the following site:
http://rtl-sdr.ru/page/vse-dostupnye-na-etom-sajte-plaginy-s-kratkim-opisani...
The site has a language translation option so you can switch the english.
On 28-12-2020 18:34, Andy Brian wrote:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Regards,
Jan PE0SAT
BTDT
Just lower your gain, the receiver is mixing close signals and cross modulation.
Make a round of tests to check what gain level gives you better results.
My experience:
* I have a near police station with a powerful 150Mhz station, any higher than 40 dB will give me splatters * Also I have a neighbor ham with an co-lineal and 50W about 400m (line of sight between antennas), if he is active on 2m local on high power gains above 28 dB will ruin my reception.
That's my experience.
El 12/28/20 a las 12:34 p. m., Andy Brian escribió:
Hi,
I received many pictures from ISS. I'm using RTL dongle 2832 with SDR# program and MMSSTV with virtual cable and Orbitron.I found many rainbow lines on pictures and I analysed that this is the case of transmission with APRS local stations around 5km away and 1mhz below my receiving. Anyone have experirence of good filtering or set the SDR# program to reduce the infulence from of transmitter which is far away from 145.8MHz but still in the 2MHz bandwidth of RTL2832?
BR Andy
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program!
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-
Andy Brian -
Armand SP3QFE -
Jean Marc Momple -
Mathison Ott -
Pavel Milanes Costa (CO7WT) -
PE0SAT | Amateur Radio -
Pedro Converso -
Samudra Haque [TTLLC]