IF bandwidth, display bandwidth, sample rate

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luv2boat
Posts: 3
Joined: Wed Jun 08, 2016 4:59 pm

IF bandwidth, display bandwidth, sample rate

Post by luv2boat » Tue Jul 26, 2016 4:17 am

Total SDR noobie.

Absolutely NO SDR experience, but easily got my new SDRplay up and running with SDRuno. For the most part it's been pretty easy to figure out basic operation and SO MUCH FUN! However, a couple of things confuse me and it is only the tip of the iceberg:

In the SDR main window:
When I mouse over the BW (bandwidth?) field it says "input sample rate". When I click on the BW field to enter a different value and mouse over the "open" BW field is says "specify amount of spectrum to view" which makes more sense.
Please help me understand the relationship between "input sample rate" and "amount of spectrum to view" in this field.

In the RSP control window:
I see that there are only discreet IF bandwidths that can be selected. Is the same true of the display bandwidth in the BW field in the main menu? Are there only discreet bandwidths that are displayed regardless of what I type in? It seems like that and often I see different display bandwidths in the spectrum window than I have selected.

I don't understand low IF and Zero IF. Is there a quick lay person explanation of the difference?

Also what is DC/IQ?

If brief explanations are difficult or time consuming, can someone point me to a good ENTRY level primer?

Many thanks!

Chris
Last edited by luv2boat on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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CaptainNemo
Posts: 146
Joined: Mon Jan 05, 2015 1:22 pm
Location: Genoa - Italy

Re: IF bandwidth, display bandwidth, sample rate

Post by CaptainNemo » Wed Jul 27, 2016 1:05 pm

Hi Chris.
I'm sdrplay user since october 2014. Relationship between those values was always a mistery to me... :D

During the first webinar some week ago I asked to have a "one page" guide to explain those relationship.
I'm sure sdrplay team will release a guide as soon as they can.

-------------------------------------------------------------------

I take the chance to say my opinion:
according to me, software functions/parameters should reflect this "logic":
1. first of all, user want to decide the "span" he/she want to see -- fulfilling the fft window
(what i want to say here is: there is no use to have a window large five inches and my "wanted" 200khz compressed in 1 inch)
2. now, software should propose the minimum SR value for that span, and oversampling SR values if there is room
3. according to values set for 1. and 2. the software should propose values for decimation if there is room

according to me this is the "order" that make sense...

bye
Last edited by CaptainNemo on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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hpkagey1
Posts: 2
Joined: Sat Jul 02, 2016 2:19 pm

Re: IF bandwidth, display bandwidth, sample rate

Post by hpkagey1 » Sat Aug 06, 2016 5:23 pm

Very good questions. A one page tutorial would be great.
Last edited by hpkagey1 on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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