FMPx steps and FFT sizes

[DaveNF2G]

I have tried Googling this and FMP stands for too many different things. Searching more broadly opens up quite a rabbit hole.

Are there compilations somewhere of the preferred step and FFT sizes for decoding the various digital protocols that DSDPlus can handle?

 

[slicerwizard]

I don't think those have anything to do with protocols.

FFT size controls how detailed the FMPx spectrum display looks and it uses more resources as you turn it and the redraw rate up.

Step size is based on the band plan. We have some VHF bands where the step size is 15 kHz, IIRC; I use 5 kHz to step through that. Most bands are 12.5 kHz; I use 6.25 kHz when tuning around in them.

 

[DaveNF2G]

Which setting(s) control the bandwidth? I see posts all the time telling someone that according to a screenshot their bandwidth is set to nnn and should be nnn for protocol x.

 

[R0am3r]

Dave - are asking about the -b command line switch?

-b<kHz> Initial RF filter bandwidth (4, 7, 9.5, 12.5, 22) [-b7]

 

[DaveNF2G]

Yes, that's what I was forgetting. Thanks!

So I'm looking for a list of preferred filter bandwidths for various digital modes.

 

[GTR8000]

Hmm, if only there were a file named FMP.txt supplied with DSDPlus that lists the bandwidth for each protocol.

 

[CanesFan95]

But if you're wanting to adjust the tuning step size, then the hotkeys are [ and ] based on what you've got in your FMPx.cfg file.

 

[DaveNF2G]

Hmm, if only there were a file named FMP.txt supplied with DSDPlus that lists the bandwidth for each protocol.

Yes, that would be nice. However, none of the 40+ directories in which I have DSDPlus et al set up have such a file.

 

[cg]

I don't know what is correct but I use the following with success:
4 - NXDN (this setting plus limiting decode to NXDN will pull in weaker NXDN signals)
7 - DMR
9.5 - P25 (OK for initial setting for P2 CC, DSDPlus will adjust)
12.5 - P25 (If I recall, seen with P25P2 voice channels, usually will work with any P25 but program will adjust)
22 - never use it

 

[pro92b]

RF bandpass filter selection

press B to cycle through filters

narrower filters reduce co-channel interference

narrower filters reduce noise levels

too-narrow filtering distorts digital waveforms


12.5 kHz

lowest CPU usage

highest noise levels

will not block co-channel signals


9.5 kHz

P25: reduces noise; eliminates most co-channel interference

NXDN9600: should work well


7 kHz

NXDN9600: should work well; low noise

DMR: matched filter


4 kHz

NXDN4800: matched filter; will eliminate most co-channel interference

D-Star: matched filter

DMR: reduces noise, but will distort waveforms (DSD+ can handle it)

 

[dave3825]

Hmm, if only there were a file named FMP.txt supplied with DSDPlus that lists the bandwidth for each protocol.

Yes, that would be nice. However, none of the 40+ directories in which I have DSDPlus et al set up have such a file.

FMP.txt came in the public version where you applied fastlane updates to, so it looks like you deleted it?





Your title says FMPx. What FMP are you using?

FMP24 2.86 says


Usage:
FMP24 [options] Normal operation
FMP24 -h Show help

Options:
-i0 Use first available RTL SDR device [-i0]
-i<num> Use RTL SDR device specified by <num> (1-255)
-i"<ser>" Use RTL SDR device with specified serial number string
-o<num> Output audio device (1-255) [-o1]
-o<linkID> Output audio DSD+ Link ID (256-65535)
-oT<port> Output audio TCP port (256-65535)
-g<num> RF gain (dB) [max]
-T<num> Enable/disable bias tee (0-1) [-T0]
-P<num> Frequency correction PPM value (-999.9-999.9) [-P0.0]
-a<num> Enable/disable auto center tuning (0-1) [-a1]
-q<num> Enable/disable squelch logic (0-1) [-q0]
-f<MHz> Initial tuned frequency [-f99.9]
-b<kHz> Initial RF filter bandwidth (4, 7, 9.5, 12.5, 22) [-b7]
-b-<kHz> Set initial RF filter bandwidth and ignore hints from DSD+
-t<num> Initial RF filter set (standard or tight) [-t0]
-u<num> Enable/disable unlicensed spectrum display (0-1) [-u0]
-z<num> Show zoomed spectrum (0-1) [-z1]
-n<num> Select noise filter (0-2) [-n0]
-v<num> Set volume level (0-500) [-v100]
-s<num> Enable/disable scanner mode (0-1) [-s0]
-e<num> Enable/disable extra CPU load to reduce I/Q dropouts [-e2]
-y<num> Select spectrum survey list file (0-999) [-y0]
-wsl<v>.<h> Spectrum window location [-wsl50.50]
-_<num> Minimize windows at startup; bitmapped
-rc Role is trunk control/rest channel monitor
-rv Role is trunk voice channel monitor

Active keys:
0-9 . Enter set frequency
[/] select step size
Cursor </> step frequency
Ctrl Csr </> step frequency by 250 Hz

A toggle auto center tuning
D cycle audio demodulation mode
Q toggle squelch mode
U toggle unlicensed spectrum display mode
M toggle spectrum memory overlay
X reset spectrum memory
Z toggle spectrum zoom overlay
I select injection mode
b/B select RF bandpass filter
T select tight or standard RF bandpass filter set
t enable/disable bias tee
N select noise filter
L toggle lost I/Q data test mode
E toggle extra CPU load to reduce I/Q dropouts
Cursor ^/v adjust volume level
spacebar toggle muting

g/G adjust RF gain
p/P adjust PPM frequency correction

R toggle raw I/Q and FM demod recording

S start scanner mode or exit hold mode
Y start spectrum survey
C start trunk control/rest channel following mode
V start trunk voice channel following mode

? list active keys
Esc exit scanner/survey/CC/VC modes or exit program

And,

FMP24.scanlist says;

; FMP24 Scan List
; ---------------
;
; Entries in this file are scanned when the 'S' key is pressed in FMP24
;
; Press Esc in FMP24 to exit scanner mode
;
; Lines with leading semicolons are ignored.
; Use a leading semicolon to "lock out" an entry.
; Use a leading semicolon to add comments/documentation.
;
; File processing stops if a line containing "<EOF>" is found.
; Entries after the <EOF> line are not processed.
;
;
; Line format:
;
; frequency options description
;
;
; Frequency is specified in MHz
;
;
; Options:
;
; Modulation Specifier
;
; 4 kHz bandwidth digital protocol specifiers:
;
; iDAS
; NX48
; NXDN48
; NEXEDGE48
;
; 7.6 kHz bandwidth digital protocol specifiers:
;
; Dstar
; D-Star
; DMR
; TRBO
; Cap+
; Con+
; TIII
; XPT
;
; 9.5 kHz bandwidth digital protocol specifiers:
;
; Fusion
; NX96
; NXDN96
; NEXEDGE96
; P25
;
; 12.5 kHz bandwidth digital protocol specifiers:
;
; PV
; ProVoice
;
; Analog modulation specifiers:
;
; AM (AM demodulation for airband)
;
; Anything else, such as "FM" or "Analog" or nothing
; is assumed to be FM modulated analog and defaults to 12.5 kHz bandwidth
;
;
; Bandwidth Specifier
;
; Overrides default bandwidth
;
; Format: BW=<kHz>
;
; Valid bandwidth values are 4, 7.6, 9.5, 12.5 and 22
;
;
; Delay Specifier
;
; Keeps FMP24 on a channel / delays resumption of scanning
; for the specified amount of time after a valid signal ends
;
; Format: DELAY=<seconds>
;
;
; Description
;
; User-supplied channel name/description
;
;
; Sample scan list:

 

[DaveNF2G]

I use FMP24 with dongles, occasionally FMPP with RSP.

FMP.txt came in the public version where you applied fastlane updates to, so it looks like you deleted it?

View attachment 172362



Your title says FMPx. What FMP are you using?




And,

My fmp24.ScanList files either have lists of frequencies to scan for the particular systems or are blank.
Nothing about filters in fmp24.cfg, which is where I would hope to be able to configure a filter setting at startup for each discrete system by having a unique config file in each system's directory. It looks like that is not possible.

EDIT: I just noticed the BW= parameter, which seems to apply to the .ScanList file rather than the .cfg file.