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Yes! ? Wild. ? It’s getting there!?

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Using basic tools like rtl_fm, no but when using say RTLSDR-Airband, you should be able to create multiple slices, pipe the audio through say netcat, and get it into multiple direwolfs.?? SDR# also now supports multiple slice receivers but I don't know if it can pipe the demodulated audio through multiple VAC (virtual audio cable) instances.?

--David
KI6ZHD

I was just reading about this in the User Guide for Direwolf, in section "9.1.6.4 Gnu Radio – multiple simultaneous channels".? That seems to be in the spirit of what you are trying to do?

Is it possible to take an SDR listening to some segment of the 2m band, and decode 1200 baud packets on multiple channels at once? 144.91, 93, 95, 97, 99, 145.01, 03, 05, 07, 09, into 10 separate ‘streams’,?

Has anybody done this yet?
Tadd - KA2DEW

On 4/2/2021 11:12 AM, David Ranch wrote:

The relays are solid state.? It is a pi hat built specifically for the low power requirements of the pi.? They can also be stacked up to 4 hats with a total of 16 relays.? I have to believe it would work well for ptt being solid state. Kenwood and others used standard contact type relays for ptt in their radios for years

You can do what you wish but using a simple transistor buffer circuit to assert PTT on your radio will provide the lowest delay and offer the highest reliability.? Up to you but yes, the use of relays to assert PTT on your radio could work.

Solid-state relays are, IIRC, functionally no different than a transistor buffer here. They're
also likely more rugged than the typical 2N7000/2N3904 sort of buffer.

73,
Dana? K6JQ

Specifically what I'm asking is if there is a way to integrate the existing control schemes that are on GitHub in python, java, and C -if there is a way to integrate those controls into direwolf?? As far as the delay, I was thinking to simply add in any necessary tx delay to the program.? I'm thinking that I saw a delay setting in either fldigi or winlink of like 250ms on tx, and I believe that would cover it.? The relays respond to bash command almost instantly- fast enough that I believe they would work after getting the delay set just right.? If I could control one relay from direwolf, then I could use another straight from the terminal to turn the radio on or off remotely, say through vnc.

--

That can be an issue, no doubt.? I believe that the major radio manufacturers have already solved that problem in the design of their ptt circuits.? I'm not looking to redesign radios.? I'm looking for a way that a pi can control any old radio without having seemingly unnecessary hardware (eg signalink or similar) involved.? At a fundamental level all you need is ptt control, audio in/out (small pot for level control), and ground.? The fact that repeater controllers are now being built on Pi's suggests that it is possible.? I'm trying to build a pi that needs only the sabrent card and a relay hat, and then with a bit of cat6 cable and a simple mic connector, any old radio can be controlled without the need for support from hamlib, flrig, etc.? The missing link is the coding necessary to use i2c control with direwolf, fldigi, etc.? It may not work, but you can't make a thing better unless you try.

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The relays are solid state.? It is a pi hat built specifically for the low power requirements of the pi.? They can also be stacked up to 4 hats with a total of 16 relays.? I have to believe it would work well for ptt being solid state.? Kenwood and others used standard contact type relays for ptt in their radios for years

You can do what you wish but using a simple transistor buffer circuit to assert PTT on your radio will provide the lowest delay and offer the highest reliability.? Up to you but yes, the use of relays to assert PTT on your radio could work.

I have 2 TR7400A's that I still use daily and no issues with the relay in either one

Those internal relays are disconnecting the receiver from the antenna to isolate it while the transmitter does it's thing.?

I'm looking for a way that the commands or some other coding could be used to control the relay from direwolf or some other program direwolf can control

Are you only looking for PTT control?? If so and at the moment, no.. Direwolf doesn't have direct "generic" I2C-based control but it does have specific GPIO support for Raspberry PI SBCs, and CM108/119 sound FOBs.? If you use Hamlib, there is some level of a foundation GPIO support that could be possibly enhanced:

??

Beyond that, I suppose Direwolf could be enhanced to add another PTT method such as "system command PTT on" and "system command PTT off".?? What I was asking in my other email was beyond PTT, is there any other generic "system command" support you would want for "relays"??? Today, Direwolf has support for signals like PTT, DCD, CON, and TXINH? (see User Guide starting with section 9.2.10+).? I currently can't think of any other signals that you might be asking of Direwolf that makes sense for an AX.25 stack.

I can't imagine that pulling the very low voltage of a ptt radio circuit to ground, or maintaining and then breaking the circuit would present any significant electrical load to the relay.

My issue wasn't around the electrical load.. it was about the additional delay that a relay introduces compared to a simple transistor circuit.

--David
KI6ZHD

On 4/2/2021 10:37 AM, hcarc.na8x@... wrote:

? I can't imagine that pulling the very low voltage of a ptt radio circuit to ground, or maintaining and then breaking the circuit would present any significant electrical load to the relay.

Counter-intuitively, a low-current load like that can run into a problem with
mechanical relays:



Solid-state relays, of course, don't have this issue.

73,
Dana? K6JQ

The relays are solid state.? It is a pi hat built specifically for the low power requirements of the pi.? They can also be stacked up to 4 hats with a total of 16 relays.? I have to believe it would work well for ptt being solid state.? Kenwood and others used standard contact type relays for ptt in their radios for years.? I have 2 TR7400A's that I still use daily and no issues with the relay in either one.? I'm looking for a way that the commands or some other coding could be used to control the relay from direwolf or some other program direwolf can control.? I can't imagine that pulling the very low voltage of a ptt radio circuit to ground, or maintaining and then breaking the circuit would present any significant electrical load to the relay.

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Hello Matt,

In the config file, it looks like you can specify more than one ADEVICE. Can you also make certain devices RX only or TX only? For an RX only I am thinking you just leave out any PTT specification?

Yes, this approach would work to effectively make it RX-only.? You do need to make sure that if you've configured Direwolf to be an APRS Igate, you don't configure it to be a full Igate (aka.. an IGATE that has transmit abilities on a given ACHANNEL).

I would like to try setting up an SDRPlay RSP1a as the receiver, and use an FM mobile radio as the TX.

This should be possible though before I can give an answer, what is your output soundcard going to be?? Do you know what sampling rates it supports?? Maybe only 48000??? Section 9.1 in the Direwolf User Guide is worth a deep read and gives a lot of general examples but nothing specific here.? Once we get something working, maybe we can get WB2OSZ to enhance his Raspberry-Pi-SDR-IGate.pdf doc to give a TX example as well.

Worst case scenario I suppose I could specify the two devices and on the TNC cable to the TX radio, leave the RX pins unconnected. I was hoping that I could disable the decoders on the TX device since it will not be receiving anything.

I think you're overthinking things here:

?? 1. Direwolf is the TNC.? You cannot mix the use of Direwolf and hardware TNCS like a Kantronics KPC3, etc.
?? 2. Direwolf's "ADEVICE" line has a receive parameter and a transmit parameter.? Whatever you DON'T use, you can specify "null" to have it essentially ignored.? If you put "null" in the transmit section, See User Guide section 9.1

Maybe you have to have them, but I could turn the sample rate way down? It would help to save some CPU cycles on the Raspberry Pi.? My goal in setting up the two devices would be for working FalconSat-3 and be able to handle doppler shift on the downlink via hamlib and GPredict.

Direwolf has an alternative way to manage CPU load.? If you look at the Direwolf User Guide section 9.2.2, there is the "/n" parameter.? As you can see here, if you're running Direwolf on an ARM processor, it's going to automatically enable a divisor of "/3".? That should be pretty good but maybe a higher divisor might work for you if you're using the newest generation Raspberry Pi SBCs like an RPI4, etc.

--David
KI6ZHD

On 4/2/2021 9:17 AM, David Ranch wrote:

Using relays for PTT is a bad idea as relays are very slow and can introduce >100ms of additional delay needed for the TXDELAY parameter.? The other issues is that relays have a finite lifespan, they can chatter when entergizing, etc).? It's far more recommended to use something solid state here.

On a tangentially-related note, I made a ring oscillator out of relays once. Be sure to turn
up the volume for full effect.



73,
Dana? K6JQ

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Hello Thomas,

Hi.? Does Direwolf support using the i2c relay boards?

Generically like sending "i2c" commands?? No, not today.

There are of course variations of this command which set the state of the other 3 relays and their 2 respective states.? I had in mind to use this hat for ptt (possibly for different radios or to eliminate needing a signalink usb) along with the sabrent usb soundcard.

Using relays for PTT is a bad idea as relays are very slow and can introduce >100ms of additional delay needed for the TXDELAY parameter.? The other issues is that relays have a finite lifespan, they can chatter when entergizing, etc).? It's far more recommended to use something solid state here.

? I've seen that Direwolf already supports the use of this card amd the associated gpio pin.? Does it/can it support the use of i2c relays?

Other than asserting a PTT signal, what other uses would you want for running a system command be it an "i2c" tool or otherwise??

--David

Hi.? Does Direwolf support using the i2c relay boards?? Currently have a 4 relay version and have control of it using commands through i2ctools using bash commands:

i2cset -y 1 0x11 0x01 0xFF

There are of course variations of this command which set the state of the other 3 relays and their 2 respective states.? I had in mind to use this hat for ptt (possibly for different radios or to eliminate needing a signalink usb) along with the sabrent usb soundcard.? I've seen that Direwolf already supports the use of this card amd the associated gpio pin.? Does it/can it support the use of i2c relays?

In the config file, it looks like you can specify more than one ADEVICE. Can you also make certain devices RX only or TX only? For an RX only I am thinking you just leave out any PTT specification? I would like to try setting up an SDRPlay RSP1a as the receiver, and use an FM mobile radio as the TX. Worst case scenario I suppose I could specify the two devices and on the TNC cable to the TX radio, leave the RX pins unconnected. I was hoping that I could disable the decoders on the TX device since it will not be receiving anything. Maybe you have to have them, but I could turn the sample rate way down? It would help to save some CPU cycles on the Raspberry Pi.? My goal in setting up the two devices would be for working FalconSat-3 and be able to handle doppler shift on the downlink via hamlib and GPredict.

On 4/1/2021 7:15 AM, Michael Champion Sr wrote:

I am curious if this applies to the SA818 chip radios as well.

Those are also based on the RDA1846(S), so it could. I've experimented with the
similar DRA818V radios and did not see the STE enabled, but I did experience
terrible TX delay; the radio keys up but takes ~700mS for audio to 'fade' in.

73,
Dana? K6JQ

Thanks,

-Michael


-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Ray Wells
Sent: Sunday, March 28, 2021 3:49 PM
To: [email protected]
Subject: Re: [direwolf] Slow PTT Release

You're running into one of numerous, and somewhat unpredictable, timing issues with the Baofeng radio. They are not suitable for packet radio, find a used "brand name" radio and use that instead.

I think you misunderstand the function of TXTAIL, which is to hold the tx up for some mS to ensure that last data packet isn't truncated if the tx drops too quickly. The last bit of data in the packet is sent during the TXTAIL period. In days of old it was almost essential for 0k3 packet on HF, and I had one commercial VHF 1k2 rig that needed a small amount of TXTAIL.

Consider that when you add extra tx time to compensate for a poor radio you are impacting performance of the entire network.

Ray vk2tv

On 29/3/21 6:53 am, Matthew Corcoran wrote:

Hi,

I'm a packet newbie and I've got direwolf working (have to say, the manual is very good :) ). I'm using USB serial PTT control with a Baofeng - PTT is quick at TX, no problems there, but a bit slow releasing so it transmits over some replies.

I've looked at TXTAIL, but it seems that also delays the PTT - Is there a way to continue the carrier for a set time without delaying the PTT. I've looked at direwolf -d o and everything seems ok there.

Cheers,

Mat.

I am curious if this applies to the SA818 chip radios as well.

Thanks,

-Michael