Search found 213 matches

by snn47
Mon Mar 09, 2020 9:43 pm
Forum: RTL-SDR Discussion
Topic: Upconverter vs. Direct Samling?
Replies: 3
Views: 5365

Re: Upconverter vs. Direct Samling?

Hotpaw I would say it depends on how you define the direct sampling setup, you use e.g. 8, 10, 12 ... Bit AD, what type of preamp if you use one, are filters used and which type HP,LPW, BP vs. the performance specs of the upconverter and by the SDR after the upconverter, you assume 8, 10, 12 ... Bit...
by snn47
Mon Mar 09, 2020 6:18 pm
Forum: RTL-SDR Discussion
Topic: Measuring VSWR
Replies: 3
Views: 5848

VSWR is important for transmitter

I wonder because I think the antenna I bought can't cover all of the HF and VHF frequency. It depends on your definition of cover. There is no antenna I know of that will support such a large range of frequency/wavelength and is matched for all frequencies. There are active antennaes that have smal...
by snn47
Mon Mar 02, 2020 11:14 pm
Forum: Antennas
Topic: Static shock while connecting ground-wire to radio?
Replies: 12
Views: 10747

Static electricity built up over time

I guess you are experiencing static electricity built up over time. If you have a coax cable then the capacity, wich will vary with cable type and length, the static electricity will accumulate over time. Did you have a thunderstorm building up in your area when you experienced this? The static elec...
by snn47
Mon Mar 02, 2020 10:47 pm
Forum: RTL-SDR Discussion
Topic: Can I use the SDR very close to the RF source?
Replies: 11
Views: 13139

Notchfilter attennuating RF source?

From what I know of comercial antenna designers and use from antennas mounted above each other vertically or horizontally separated, you cannot achieve at best 20 dB of isolation if you really put a lot of work into optimizing your antenna placement using meassuring equipment for finding the best is...
by snn47
Mon Mar 02, 2020 9:54 am
Forum: RTL-SDR Discussion
Topic: Can I use the SDR very close to the RF source?
Replies: 11
Views: 13139

PAPR and RMS of modulation

Thank you, that is what I assumed, the Diodes are clipping to protect. PS:it can be two causes that destroy the receiver, either a to high voltage generated by the modulation power that will destroy the diodes junktion this is why PAPR is important and/or a to high continious RF RMS power power of t...
by snn47
Sat Feb 29, 2020 4:54 am
Forum: RTL-SDR Discussion
Topic: Can I use the SDR very close to the RF source?
Replies: 11
Views: 13139

Re: Can I use the SDR very close to the RF source?

@rtlsdr max input power of an R820T2 is +10dBm Does this apply to the RTL-820T2 input without or with the antiparalell protecting diodes that I remember having seen. Do you know the max. PAPR (Peak To Average Ratio) for the +10 dBm value, which is also important to know, since the PAPR for OFDM can ...
by snn47
Wed Feb 26, 2020 5:56 am
Forum: Signal Identification Help
Topic: AM-radio with unstable frequency?
Replies: 4
Views: 8564

Re: AM-radio with unstable frequency?

It could just be receiver intermodulation. If you have a 10 or 20 dB attenuator insert it and see if you still receive the station.
by snn47
Wed Feb 26, 2020 5:48 am
Forum: RTL-SDR Discussion
Topic: Bluetooth Classic Sniffing
Replies: 3
Views: 4873

Re: Bluetooth Classic Sniffing

Even if you use a converter that would mix the BT-frequencies to below 1700 MHz, you would need also to be able to folloe the frequency hopping pattern of BT see https://en.wikipedia.org/wiki/Bluetooth
by snn47
Wed Feb 26, 2020 5:36 am
Forum: RTL-SDR Discussion
Topic: Received Audio
Replies: 1
Views: 3691

Re: Received Audio

Audio for voice from my HP Z-books isn't to bad so I havn't had the need to use external speaker. If I did I would use one of my BT speakers on battery to avoid humming from an AC loop.
vy 73
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by snn47
Wed Feb 26, 2020 5:26 am
Forum: RTL-SDR Discussion
Topic: Can I use the SDR very close to the RF source?
Replies: 11
Views: 13139

Re: Can I use the SDR very close to the RF source?

Why do you want to place the SDR antenna so close to the transmitter antenna ? Even a 50 ohm termination on your SDR should be enough to receive the transmitted signal at this distance and make it safe for your SDR. With antennas at VHF beeing about 1 m appart you cannot calculate/estimate the isola...