Search found 90 matches

by alanzfq
Tue Apr 07, 2020 7:26 am
Forum: RTL-SDR Discussion
Topic: Performance of R820T v3 dongle
Replies: 7
Views: 488

Re: Performance of R820T v3 dongle

I'm well aware of the way HDSDR and other software hides the centre spike.
But how many SDRs have you tried? Some of them have very low spikes. I'm not talking RTL exclusively.
Alan
by alanzfq
Mon Apr 06, 2020 8:09 am
Forum: RTL-SDR Discussion
Topic: Performance of R820T v3 dongle
Replies: 7
Views: 488

Re: Performance of R820T v3 dongle

It is my understanding that it is a balance defect in the ADC that produces the centre spike. It is at zero frequency nothing can be received.
Some are better than others, some give a big spike, others much smaller. As you say, software usually greatly reduces it and it's effects.
Alan
by alanzfq
Fri Apr 03, 2020 7:18 am
Forum: RTL-SDR Discussion
Topic: Performance of R820T v3 dongle
Replies: 7
Views: 488

Re: Performance of R820T v3 dongle

Many SDRs work like this. In the exact centre they receive nothing. The reason is that they act as a direct conversion receiver, the oscillator is in the centre. You do not see this. Signals are received both sides. The IQ processing determines which side a signal really is. Always use an offset, do...
by alanzfq
Sun Mar 29, 2020 4:22 pm
Forum: RTL-SDR Discussion
Topic: VLF kit for a newbie
Replies: 2
Views: 321

Re: VLF kit for a newbie

What do you mean by VLF?
"HF Direct Sampling Mode - Listen to 500 kHz - 24 MHz with direct sampling."
500Khz is not what many call VLF...
You must find someone that knows the antenna or get a honest write-up, if it overloads then it will be useless.
Alan
by alanzfq
Sat Mar 28, 2020 8:34 am
Forum: RTL-SDR Discussion
Topic: Direct Sampling
Replies: 5
Views: 546

Re: Direct Sampling

https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ Please read this HF Direct Sampling Mode - Listen to 500 kHz - 24 MHz with direct sampling. Simply connect an HF antenna to the SMA port, and choose the Q-branch mode. There is a built in 25 MHz low pass filter, but additional HF filters may be requ...
by alanzfq
Fri Mar 27, 2020 4:58 pm
Forum: RTL-SDR Discussion
Topic: List of Weather Fax emitters
Replies: 1
Views: 345

Re: List of Weather Fax emitters

I looked recently found it easily with a Google search, sorry did not keep the link
Alan
by alanzfq
Fri Mar 27, 2020 4:55 pm
Forum: RTL-SDR Discussion
Topic: Direct Sampling
Replies: 5
Views: 546

Re: Direct Sampling

Perhaps you need to read up on what you bought?
Direct sampling is used for reception below 24MHz
Alan
by alanzfq
Sun Mar 22, 2020 8:09 am
Forum: RTL-SDR Discussion
Topic: software for RTL-SDR RTL2832U DVB-T Tuner Dongle
Replies: 15
Views: 7947

Re: software for RTL-SDR RTL2832U DVB-T Tuner Dongle

You cannot make any accurate measurements unless you have a standard to calibrate your receiver.
Comparative measurements are easy, but accurate measurements require an accurate generator.
Alan
by alanzfq
Thu Mar 19, 2020 7:20 am
Forum: RTL-SDR Discussion
Topic: Passive radar for sounding ice sheets?
Replies: 1
Views: 921

Re: Passive radar for sounding ice sheets?

Perhaps if you supply more details.
Personally I do not have enough interest to register and to sign in on that link.
Alan
by alanzfq
Thu Mar 19, 2020 7:16 am
Forum: RTL-SDR Discussion
Topic: Can I observe TV channels using an rtl2832u?
Replies: 6
Views: 3154

Re: Can I observe TV channels using an rtl2832u?

Yes, using software intended for TV use.
But you can not use the RTL as an SDR with that software.
It seems a little OT for this group but a search could find suitable software.
A Google of "rtl dongle view TV" seems to show some possibles.
Alan