SDRuno MW/FM Broadcast Notch

Discussions about everything to do with SDRuno
Kevin
Posts: 12
Joined: Sun Mar 26, 2017 9:29 pm

SDRuno MW/FM Broadcast Notch

Postby Kevin » Sun Aug 19, 2018 11:35 pm

Just wondering why the MW/FM Broadcast Notch filter cannot be employed in the Hi Z antenna position. Using the ANT A position works but at reduced signal strength because I'm using a discone antenna for ANT A.

Kevin

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g1hbe
Posts: 363
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: SDRuno MW/FM Broadcast Notch

Postby g1hbe » Sun Aug 19, 2018 11:42 pm

If you take a look at the block diagram, you will see that the Hi-z antenna goes in at a much later stage than the A and B ports, bypassing the filters and notches. It's a bit of a mixed bag - it misses out on the filtering and notching, but it's actually a quieter receiver better suited to HF and lower bands. It's superb at LF and VLF and long as you put a LPF in line.

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Andy

Kevin
Posts: 12
Joined: Sun Mar 26, 2017 9:29 pm

Re: SDRuno MW/FM Broadcast Notch

Postby Kevin » Sun Aug 19, 2018 11:53 pm

Hi Andy,
Thanks for the quick reply. Understand the diagram, however it seems the software could resolve the switching issue to use the MW/FM notch in the Hi z position. Here in NY City the filter would be useful I'm sure as it does help in ANT A position. Just a thought in experimenting.

Kevin

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SDRnerd
Posts: 21
Joined: Sun Jan 07, 2018 6:29 pm

Re: SDRuno MW/FM Broadcast Notch

Postby SDRnerd » Mon Aug 20, 2018 8:33 am

It depends wich SDRplay you are using. Maybe its best to say what model you are using.
The RSPduo has a separate MW/FM notch that operates before the signal meets the 50 Ohm signal path of tuner 1..
Andy comments on the RSP2 diagram.

73' Ron

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Roger
Posts: 154
Joined: Fri Dec 29, 2017 7:59 pm

Re: SDRuno MW/FM Broadcast Notch

Postby Roger » Mon Aug 20, 2018 4:28 pm

The RSP2 does not have a HiZ hardware MW rejection filter and the software cannot enable something which does not exist. However there is one in the AntA/B hardware circuit if you need to use this feature. The RSPduo has better Hi-Z front end RF filters, which reduces spurious signals, and a hardware MW/FM band reject filter which can be turned on by software. The RSP1A also works well on HF and it includes a MW/FM band reject filter.

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Kevin
Posts: 12
Joined: Sun Mar 26, 2017 9:29 pm

Re: SDRuno MW/FM Broadcast Notch

Postby Kevin » Tue Aug 21, 2018 2:24 pm

Thank you for the comments so far, however understanding that the RSP2 doesn't support a MW/FM filter in the HI Z position it does have it in the other two antenna ports with reduced sensitivity because of the antenna used (discone). The question remains if the other RSP's can do it why can't the software for the RSP2 be included. Is the hardware of the other models preventing a software change? Not being a software wiz and trying to understand why not.

Kevin

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Tech_Support
Posts: 366
Joined: Mon Jun 01, 2015 7:00 pm

Re: SDRuno MW/FM Broadcast Notch

Postby Tech_Support » Tue Aug 21, 2018 2:48 pm

Hello Kevin,
The RSPduo is the only other device that has a notch filter on the Hi-Z port and it is a completely different hardware design. The limitation with the RSP2 is hardware not software. The Hi-Z port has a completely different characteristic impedance and requires a totally different design for this filter. The Hi-Z port is also balanced and so the filter needs also to be balanced.

Sincerely

Tech_Support

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Kevin
Posts: 12
Joined: Sun Mar 26, 2017 9:29 pm

Re: SDRuno MW/FM Broadcast Notch

Postby Kevin » Sat Aug 25, 2018 11:54 pm

Now we're getting somewhere. Thank you Tech-Support for the explanation and understanding.

Kevin ;)

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