Search found 253 matches

by snn47
Tue Dec 15, 2020 11:11 am
Forum: Other SDR Devices
Topic: HackRF One, ADALM-PLUTO comparison, or other possibilities
Replies: 6
Views: 2763

Re: HackRF One, ADALM-PLUTO comparison, or other possibilities

Hello Kevin, 1. If the IM distorion is within your receiver attenuating all signals will also reduce the burden on your RX. e.g. take a 20 dB preamp it will amplify a single -90 dBm to -70 dBm, or a single -20 dBm signal to 0 dBm. If it cannot amplify the -20 dBm by 20 dB to 0 dBm it is in compressi...
by snn47
Tue Dec 15, 2020 10:38 am
Forum: Off-Topic
Topic: Is it my old age?
Replies: 10
Views: 3395

Re: Is it my old age?

I remember a few publications for preamps receiving Wx-satellite e.g. in UKW-Berichte/VHF Communication Magazine, which employed simple LC filter with air inductor and FET. More recent design employ integrated LNA for RTL-SDR, e.g. DG8GB http://www.gunthard-kraus.de/Vortrag_Weinheim/Weinheim_2014.pd...
by snn47
Sun Dec 13, 2020 7:03 pm
Forum: Antennas
Topic: What coax
Replies: 3
Views: 1091

Re: What coax

Some guidance for choosing coax cable here viewtopic.php?f=6&t=4861&p=12432#p12432. It depends on the max. overall attenuation at 2m/70 cm that you willing to accept. While a LNA will compensate distribution loss, you properbly have to use filter when you have strong transmitter, espceically 2m/70 c...
by snn47
Sun Dec 13, 2020 6:47 pm
Forum: Off-Topic
Topic: Is it my old age?
Replies: 10
Views: 3395

Re: Is it my old age?

The BP filter diagram that aurgathor attached looks like a low pass filter to me, even though the text suggests otherwise.

Using the same website I get a different diagram
_#.PNG
_#.PNG (8.76 KiB) Viewed 1933 times
I personally would use a helical, or better a cavity bandpath filter. Just look for a 2m BP filter.
by snn47
Wed Dec 09, 2020 7:01 pm
Forum: RTL-SDR Discussion
Topic: Performance expectations for RTL-SDR dongle
Replies: 6
Views: 1674

Re: Performance expectations for RTL-SDR dongle

What you observed can be explained by different effects influencing reception, but you have to find out which or which combination it is at your location, if it is a overloded Rx or another reason. Antenna pattern and resonance inside vs. outside: Unless an antenna is in free space, meaning well abo...
by snn47
Tue Dec 08, 2020 2:18 pm
Forum: Other SDR Devices
Topic: HackRF One, ADALM-PLUTO comparison, or other possibilities
Replies: 6
Views: 2763

Re: HackRF One, ADALM-PLUTO comparison, or other possibilities

Would placing a bandpass filter for the frequencies of interest ahead of the SDR increase sensitivity for those frequencies? Is that what you are meaning? No, I know it is not the simple answer you have hoped for, but it depends on the number of interfering signals and their strength and how many M...
by snn47
Mon Dec 07, 2020 7:47 pm
Forum: Off-Topic
Topic: What is the time out for writing replies on the board
Replies: 1
Views: 730

What is the time out for writing replies on the board

Since this is not the first time that the board logged me out during a longer detailed reply I would like to ask the question how long will I stay logged into the board? Like several times before, I just had finished my reply and wanted to preview my reply. The board required me to login again. Unfo...
by snn47
Tue Dec 01, 2020 6:06 pm
Forum: Other SDR Devices
Topic: I have a PAL and FM TV tuner card, can I use this as SDR?
Replies: 3
Views: 1889

Re: I have a PAL and FM TV tuner card, can I use this as SDR?

Internal and external PAL and FM tuner cards were built to cover the terrestrial analogue and/or DVB BC and TV channels. Those internal cards external boxes consist of a turner and a circuit for converting the signals for the pc. To my knowledge only some of those DVB (?), may be used as SDR, while ...
by snn47
Tue Dec 01, 2020 5:51 pm
Forum: Other SDR Devices
Topic: HackRF One, ADALM-PLUTO comparison, or other possibilities
Replies: 6
Views: 2763

Re: HackRF One, ADALM-PLUTO comparison, or other possibilities

There is no simple answer to your question, it depends on the frequency range and bandwidth you want to monitor. The intermodulation free dynamic range (ratio of strong to weak signals received) limits the sensitivity you can achieve. How strong would undesired signals be at your receiver input? Eve...
by snn47
Tue Dec 01, 2020 5:29 pm
Forum: Antennas
Topic: What is the device called that automatically points the antenna toward a satellite as it passes across the sky?
Replies: 1
Views: 1201

Re: What is the device called that automatically points the antenna toward a satellite as it passes across the sky?

What dish size and what tracking range do you need, what type of satellite do you want to track in orbit or geostationary? For small dishes used in airplanes and ships they are called Automatic Tracking Satellite Dish. If you look for sate TV you can find two motor driven actuator mounts for steerin...