External digital S-Meter

The place to talk about specific amateur radio equipment and all types of accessories, fixes, repairs and modification.
Post Reply
User avatar
andrew30
Regular
Regular
Posts: 46
Joined: 18 Sep 2018, 14:03
Call Sign: 329TM1

External digital S-Meter

Post by andrew30 »

Hi,
is there a S-Meter with standard 0-3.3V input which would show not just S-units but also equivalent dBm with possibly 1dBm precision?
HFDX
Regular
Regular
Posts: 47
Joined: 27 Jan 2011, 15:10

Re: External digital S-Meter

Post by HFDX »

No
User avatar
andrew30
Regular
Regular
Posts: 46
Joined: 18 Sep 2018, 14:03
Call Sign: 329TM1

Re: External digital S-Meter

Post by andrew30 »

What makes it impossible to exist?
I suppose project based on Arduino Nano + 16x2 LCD should be possible.
All that's required is to measure input voltage and convert it to corresponding dBm value.
2-3 calibration points and it should be set to go...
User avatar
Tigersaw
Radio Addict
Radio Addict
Posts: 895
Joined: 19 Oct 2013, 15:48
Call Sign: GW6RRL
Location: Llanwrtyd Wells Powys
Contact:

Re: External digital S-Meter

Post by Tigersaw »

I did a similar thing some moons ago with an Arduino but used the 4 bit digital S meter output of the FT857 to drive a display.
https://www.youtube.com/watch?v=3LNirO7Wi58
User avatar
andrew30
Regular
Regular
Posts: 46
Joined: 18 Sep 2018, 14:03
Call Sign: 329TM1

Re: External digital S-Meter

Post by andrew30 »

Wow, this looks interesting!
Can you get dBm values out of FT817/857 through CAT ?
User avatar
Tigersaw
Radio Addict
Radio Addict
Posts: 895
Joined: 19 Oct 2013, 15:48
Call Sign: GW6RRL
Location: Llanwrtyd Wells Powys
Contact:

Re: External digital S-Meter

Post by Tigersaw »

andrew30 wrote: 23 Sep 2018, 10:06 Wow, this looks interesting!
Can you get dBm values out of FT817/857 through CAT ?
No, its just a 4 bit number corresponding to the bargraph S meter on the front, I think it corresponds to
0,1,2,3,4,5,6,7,8,9,+10,+20,+30,+40,+50 or something like that, the FT857 has a very inaccurate meter.
It does have a 0-10ma (or could be 0-1ma, 0-100ma) analogue output as well for an external meter.

S meter levels are relative anyway, no two radios seem to read the same, and if you use RF gain to get the best SNR then you cant really use them to give signal reports. Thats why a report of 5/9 or 5/9+10 is meaningless, it should be a quantitative assessment based on:
1 Faint—signals barely perceptible
2 Very weak signals
3 Weak signals
4 Fair signals
5 Fairly good signals
6 Good signals
7 Moderately strong signals
8 Strong signals
9 Extremely strong signals

Your best bet of getting dBm values that can be compared day to day I would think would be with a SDR setup, I know SDRconsole can be set to show received dBm
Post Reply