Welcome to the FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
Need the latest SmartSDR or 4O3A Genius Product Software?


SmartSDR v4.0.1 and the SmartSDR v4.0.1 Release Notes

SmartSDR v3.10.15 and the SmartSDR v3.10.15 Release Notes

The latest 4O3A Genius Product Software and Firmware
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

S-Meter without signals covered by TNF

Member, Super Elmer Moderator
in New Ideas

I have some pretty bad carriers that I can easily notch out with the TNF. The problem is that they show on the S-Meter, even with the TNF engaged. I would like to see the S-Meter cover only signals not covered by any TNFs in the passband.

2
Up Down
2 votes

Open for Comments · Last Updated

Comments

  • Member ✭✭✭✭
    edited April 2021

    Well, the basic answer is that the TNF works in the audio portion of the radio, and the S meter reading is based on the signal strength at the antenna connection before filtering. This is different than a traditional superhet where the S meter is typically in the IF stage after filtering. But the flex has no IF, being direct sampling of the rf to an ADC for processing by software. Steve Hicks from flex has a recent YouTube video on this. I had the same question, but got the above answer at the flex booth at a ham fest.

  • Member, Super Elmer Moderator

    The S-Meter only takes into account what is in the passband. Signals 10 Hz outside the filter have no influence at all (gotta love DSP!!). It is a matter of programming to remove the TNF slice(s) from the data that comprises the filter passband. Not a trivial task I would imagine, but certainly possible. It may not be worth doing if it would increase latency appreciably (maybe a Flex engineer could comment on this).

    The S-Meter does not "see" the antenna connection, it is software that processes the data once the RF signal has been digitized in the ADC. It is coded such that it only uses the data within the filter passband. If this were not so, then the largest signal on the panadapter would generate the S-Meter reading.

Leave a Comment

Welcome!

It looks like you're new here. Sign in or register to get started.
Sign In
Register
New Idea

Quick Links

Categories