DSDPlus FMP24: reduce swath of monitored spectrum?

[polkaroo]

Is there a way to reduce the swath of spectrum that FMP24 monitors to reduce data load on the USB with multiple receivers working simultaneously? I have no need to watch anything other than the tuned frequency feeding DSDPlus and it doesn't do multiple VFOs, so it's wasted CPU cycles.

 

[phyberoptics]

No, the window width must be 1024. Some settings can be adjusted in FMP.cfg, fmp24.cfg or fmpa.cfg

 

[polkaroo]

I didn't mean the window width (though it would affect it) however I did forget about the .cfg files, thought it was all command line switches. What I was looking for was 2.4 ; sampling rate (1.0, 2.0 or 2.4)

but seems that it's a depreciated option as FMP24 gives me an error that sampling rate must be 2.4.

 

[thewraith2008]

FMP24 is fixed to 2.4MSPS.
The old FMP (public release) is 1.0MSPS.

The 1st line 'option' (sampling rate) in the .cfg has never functioned as far as I'm aware (to be able to change sampling rate).

In theory it would be good to use a lower samplerate for the reasons you mentioned, but the RTL works poorly when you go under 1.0MSPS.
If you decimate the full 2.4MSPS down to something else (decimate x64 = 37.5KHz) that works OK but your still using the 'full' bandwidth of the USB.

 

[Forts]

I have 5 sdr's plugged into 1 machine (an older Core i3 desktop) running 5 instances of FMP24 & DSD+... CPU load sits at around 10% and I have no issues at all. Keeping the FMP24 spectrum display minimized will help keep load down too.

 

[polkaroo]

I have 6 sticks plugged in... the unfortunate thing is a fly's fart would make FMP24 scream errors. I've already used a dentist pick to try to wedge the USB hub's pins tighter against the SDR sticks'. I'm not sure whether lower USB bandwidth usage would help.

 

[a417]

I have 6 sticks plugged in... the unfortunate thing is a fly's fart would make FMP24 scream errors. I've already used a dentist pick to try to wedge the USB hub's pins tighter against the SDR sticks'. I'm not sure whether lower USB bandwidth usage would help.

Do you have them all plugged in to the same root hubs?

 

[polkaroo]

Yes, it's on a 7 port hub with a power supply. It's been working fine for a couple years. I've saturated the hub and SDR stick pins with contact cleaner, hope it works better.

 

[a417]

Yes, it's on a 7 port hub with a power supply. It's been working fine for a couple years. I've saturated the hub and SDR stick pins with contact cleaner, hope it works better.

A USB root hub is not the same as a USB "hub"/port multiplier/powered hub.

The root hub is inside your computer and is [probably] a port on a chip that provides USB data thruput for its downstream devices. Modern computers have several/many of these as many different internal and external devices use USB.

My computer motherboard provides 5.

1. Internal USB 1.1/2.0 for the usb ports for the keyboard & mouse (these are preferred for keyboard/mouse as they enumerate first for the BIOS to allow them to work better on boot control)
2. USB 2.0 Root hub for the 2.0 backplane connectors
3. USB 3.x Root hub for the 3.0 backplane connectors
4. USB 2.0 Root hub for the headers that connect to the front panel USB ports
5. USB 3.x Root hub for the headers that connect to the front panel USB ports.

If you have all those devices plugged into a single USB port multiplier, they are all likely hammering on a single USB root hub controller...likely saturating it and giving you the problems. It's probably not physical (with the hub/contacts), it's probably a bandwidth issue.

There are a variety of ways you can see which ports connect to which root hubs, but once you figure out which ports are being controlled by which ones, you can spread the load out amongst the various root hubs and see if your litany of USB errors goes away.

I dislike those large port # powered hubs for things that require large (continuous) bandwidth transfers, primarily for bottlenecking issues like this (which is what my amateur opinion is). Instead of 1 large 7 port pushing all those bits down essentially 2 data wires, try doing 2 or 3 to each root hub and see if it goes away.

As @Forts mentioned earlier, computers with diminished horsepower can still handle multiple streams. I personally have an XP (pentium 2 nonsense) box running 3 instances of DSD+. If i plug them all into a port multiplier on a single root hub, it barfs. If I spread them out and make the appropriate sacrifice, it will run them w/o issue.

 

[polkaroo]

The computer is an old laptop. I prefer to use a laptop as its battery is somewhat of a UPS. I do monitor it from time to time for bulging, just in case.

From what I gathered, there's two controllers - one USB 2.0 and USB 3.0 each. The internal trackpad, keyboard, etc. would all be USB 2.0 and nothing USB 3.0 so that the hub is connected to the USB 3.0 port. Now, for years, it was working just fine. It's only in the last few months that it's been giving me problems. Hopefully the contact cleaner will give a new lease on life.

 

[a417]

The computer is an old laptop. I prefer to use a laptop as its battery is somewhat of a UPS. I do monitor it from time to time for bulging, just in case.

From what I gathered, there's two controllers - one USB 2.0 and USB 3.0 each. The internal trackpad, keyboard, etc. would all be USB 2.0 and nothing USB 3.0 so that the hub is connected to the USB 3.0 port. Now, for years, it was working just fine. It's only in the last few months that it's been giving me problems. Hopefully the contact cleaner will give a new lease on life.

View attachment 95997

USB 3.0 hubs with USB 2.0 devices in them will fall back to USB 2.0 compatibility mode, they won't run any faster.

What makes you think it's cruddy connectors?

 

[polkaroo]

Yes understood - but there's nothing else on the USB 3.0 ports, so might as well use that for the sticks.

Well, it's been about 24 hours and so far so good.

 

[dave3825]

I have 6 sticks plugged in... the unfortunate thing is a fly's fart would make FMP24 scream errors

Ha ha. I get that with my airspy mini on UT2. I thought it was the usb extension cable so I bought another. Same thing. The smallest movement disconnects and reconnects it and it messes up UT. I run Unitrunker with the mini and when the disconnect reconnect happens, the whole pc becomes very slow and painful to use. Takes 5 minutes to shut down Unitrunker. Then all is good.

I cleaned the mini's contacts made no difference. It could be a bad solder joint. It does not happen when our webcam gets bumped while my son is remote learning using the same usb extension cable. That's why I am leaning to a solder joint.

 

[polkaroo]

The contact cleaning seems to have helped? *knock on wood*

I suppose the extreme end of fixing things would be to solder the SDR sticks to the USB hub itself. The strain from the weight and size of the SDR devices plugged directly into a USB port doesn't exactly help either. I guess it saves the manufacturer a few cents and not have to include a separate USB cable. Because cabled connections to other high-throughput devices like hard drives seem pretty solid. I don't hear the random disconnect/connect sounds from those. It's only the SDR sticks that are causing grief!

 

[polkaroo]

Well, so far so good... a week's gone by and no issues. I guess it was oxidized/dirty contacts afterall.

 

[dave3825]

I suppose the extreme end of fixing things would be to solder the SDR sticks to the USB hub itself.

That's what I am working on. I have a 3.5 hdd aluminum case and a small car amplifier thats been stripped. I also have a 7 port usb hub laying around collecting dust and an LNA that has no case, like this,

Plan is to strip the plastic housing off the hub and mount the hub inside the hdd enclosure. Then solder 4 nooelec dongles to it. Since I normally run 8 dongles off the same antenna, I am going to try to mount a 4 way splitter and the LNA inside and have just one ant port sticking out. I have everything I need except for some uninterrupted time (kids and remote learning ). Just need some thermal tape or thermal paste.