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A Simple Portable Packet Station for Emergency Communications


Richard Bates
 

Described here is a simple portable packet station for emergency communications that can be used to connect to a packet node, to send & receive messages. 

The hardware consists of a Raspberry Pi (RPi), a USB Sound Adapter, a reed relay, a general-purpose radio, a smartphone and a battery. The Sound Adapter connects to the radio's microphone and speaker; one of the RPi GPIO pins connects to a reed relay whose contacts drive the radio PTT. This first figure shows the hardware, without the smartphone.


On boot up the RPi runs the Pat email client and Direwolf as a AX.25 packet modem/TNC, to interface with the radio; the RPi also operates as a hotspot, so the user connects to it with a smartphone web browser using WiFi, to operate Pat. 
 
This second figure shows the Pat web browser dialog on the smartphone, connecting from the portable station to a packet node, to send a message.



At the end of the session, the RPi can be safely powered down using an added push-button, as described here; thus the user does not need to issue any linux commands on the RPi.
 
Incidentally, the AnyTone AT-D868UV is attractive as an all-purpose emergency HT, as it can be programed to operate on analog amateur bands, as well as fire, police and ambulance service, marine and FRS/GMRS frequencies. (This and the newer version, AT-D878UV, have beeen positively reviewed in the 11/2018 and 7/2019 issues of QST, respectively)
 
Please let me know if you would like more details about this project.

Richard


Brian Webster
 

Richard,

                Great project! I am interested in this project very much. I have been wanting to find some sort of appliance device that we can get new hams on the air with packet who may have not been around years ago when it was more popular. Quite a few have tried APRS but most simple solution use VOX and don’t address the hardware PTT solution you have. I find even with hardware PTT solutions many of the Chinese radios don’t work well on connected packet due to the fact that the recovery time for the receiver after a transmit is too slow to receive ack packets from the other end of a link. That is just something where education addresses that problem. Do you have a disk image set up for the Pi to run this solution? Also do you have a user guide geared towards packet newbies to help set this up? We have a good functional packet network here in the Northeast US that we want to get more users active and train them what they can do on the network once connected https://www.eastnetpacket.org/

 

 

Thank You,

Brian N2KGC

 

From: RaspberryPi-4-HamRadio@groups.io [mailto:RaspberryPi-4-HamRadio@groups.io] On Behalf Of Richard Bates
Sent: Tuesday, June 18, 2019 8:22 AM
To: RaspberryPi-4-HamRadio@groups.io
Subject: [RaspberryPi-4-HamRadio] A Simple Portable Packet Station for Emergency Communications

 

Described here is a simple portable packet station for emergency communications that can be used to connect to a packet node, to send & receive messages. 

The hardware consists of a 
Raspberry Pi (RPi), a USB Sound Adapter, a reed relay, a general-purpose radio, a smartphone and a battery. The Sound Adapter connects to the radio's microphone and speaker; one of the RPi GPIO pins connects to a reed relay whose contacts drive the radio PTT. This first figure shows the hardware, without the smartphone.

On boot up the RPi runs the Pat email client and Direwolf as a AX.25 packet modem/TNC, to interface with the radio; the RPi also operates as a hotspot, so the user connects to it with a smartphone web browser using WiFi, to operate Pat. 

 

This second figure shows the Pat web browser dialog on the smartphone, connecting from the portable station to a packet node, to send a message.

At the end of the session, the RPi can be safely powered down using an added push-button, as described here; thus the user does not need to issue any linux commands on the RPi.

 

Incidentally, the AnyTone AT-D868UV is attractive as an all-purpose emergency HT, as it can be programed to operate on analog amateur bands, as well as fire, police and ambulance service, marine and FRS/GMRS frequencies (This and the newer version, AT-D878UV, have beeen positively reviewed in the 11/2018 and 7/2019 issues of QST, respectively)

 

Please let me know if you would like more details about this project.

Richard


Ronny Julian <k4rjjradio@...>
 

I like it except for the soldering.  Not exactly appliance compliant.  My vision will not let me do the soldering.

On Tue, Jun 18, 2019 at 8:40 AM Brian Webster via Groups.Io <radiowebst=yahoo.com@groups.io> wrote:

Richard,

                Great project! I am interested in this project very much. I have been wanting to find some sort of appliance device that we can get new hams on the air with packet who may have not been around years ago when it was more popular. Quite a few have tried APRS but most simple solution use VOX and don’t address the hardware PTT solution you have. I find even with hardware PTT solutions many of the Chinese radios don’t work well on connected packet due to the fact that the recovery time for the receiver after a transmit is too slow to receive ack packets from the other end of a link. That is just something where education addresses that problem. Do you have a disk image set up for the Pi to run this solution? Also do you have a user guide geared towards packet newbies to help set this up? We have a good functional packet network here in the Northeast US that we want to get more users active and train them what they can do on the network once connected https://www.eastnetpacket.org/

 

 

Thank You,

Brian N2KGC

 

From: RaspberryPi-4-HamRadio@groups.io [mailto:RaspberryPi-4-HamRadio@groups.io] On Behalf Of Richard Bates
Sent: Tuesday, June 18, 2019 8:22 AM
To: RaspberryPi-4-HamRadio@groups.io
Subject: [RaspberryPi-4-HamRadio] A Simple Portable Packet Station for Emergency Communications

 

Described here is a simple portable packet station for emergency communications that can be used to connect to a packet node, to send & receive messages. 

The hardware consists of a 
Raspberry Pi (RPi), a USB Sound Adapter, a reed relay, a general-purpose radio, a smartphone and a battery. The Sound Adapter connects to the radio's microphone and speaker; one of the RPi GPIO pins connects to a reed relay whose contacts drive the radio PTT. This first figure shows the hardware, without the smartphone.

On boot up the RPi runs the Pat email client and Direwolf as a AX.25 packet modem/TNC, to interface with the radio; the RPi also operates as a hotspot, so the user connects to it with a smartphone web browser using WiFi, to operate Pat. 

 

This second figure shows the Pat web browser dialog on the smartphone, connecting from the portable station to a packet node, to send a message.

At the end of the session, the RPi can be safely powered down using an added push-button, as described here; thus the user does not need to issue any linux commands on the RPi.

 

Incidentally, the AnyTone AT-D868UV is attractive as an all-purpose emergency HT, as it can be programed to operate on analog amateur bands, as well as fire, police and ambulance service, marine and FRS/GMRS frequencies (This and the newer version, AT-D878UV, have beeen positively reviewed in the 11/2018 and 7/2019 issues of QST, respectively)

 

Please let me know if you would like more details about this project.

Richard


Richard Bates
 

Brian

> .... disk image ..... user guide....

OK - I'll work on these two items in the next week - and post it here.

Richard 


Richard Bates
 

On Tue, Jun 18, 2019 at 08:45 AM, Ronny Julian wrote:
except for the soldering. 
I think it's unavoidable when using a general-purpose radio - to create the cables to go between the USB sound adapter & radio audio, and between the GPIO relay & radio PTT.

If you can spring for the Kenwood TH-D72A, then you can avoid this - this radio has a built-in TNC, so you can use an off-the-shelf USB cable (A-Male to Mini-B) between the RPi and radio.

Richard


Brian Webster
 

One suggestion may be to propose a more standard connection. There are a couple of popular connection methods, one is the mini DIN on the back of some radios, the other is the kantronics 9 pin connector method and the other is the older 5 pin DIN used in many of the older packet TNC’s. The idea being that if someone could make up a batch of cables that mate up to one or more of these methods, a user can normally find packet cables for their particular radio from various sources. I know you are probably not wanting to build and sell cables but documenting this could maybe assist others who could make one for this person or maybe if the project takes off someone will start to manufacture them for this device.

 

Thank You,

Brian N2KGC

 

From: RaspberryPi-4-HamRadio@groups.io [mailto:RaspberryPi-4-HamRadio@groups.io] On Behalf Of Richard Bates
Sent: Tuesday, June 18, 2019 9:02 AM
To: RaspberryPi-4-HamRadio@groups.io
Subject: Re: [RaspberryPi-4-HamRadio] A Simple Portable Packet Station for Emergency Communications

 

On Tue, Jun 18, 2019 at 08:45 AM, Ronny Julian wrote:

except for the soldering. 

I think it's unavoidable when using a general-purpose radio - to create the cables to go between the USB sound adapter & radio audio, and between the GPIO relay & radio PTT.

If you can spring for the Kenwood TH-D72A, then you can avoid this - this radio has a built-in TNC, so you can use an off-the-shelf USB cable (A-Male to Mini-B) between the RPi and radio

Richard


 

Unless you switch to DRAWS™ 


On Tue, Jun 18, 2019, 06:02 Richard Bates <richard@...> wrote:
On Tue, Jun 18, 2019 at 08:45 AM, Ronny Julian wrote:
except for the soldering. 
I think it's unavoidable when using a general-purpose radio - to create the cables to go between the USB sound adapter & radio audio, and between the GPIO relay & radio PTT.

If you can spring for the Kenwood TH-D72A, then you can avoid this - this radio has a built-in TNC, so you can use an off-the-shelf USB cable (A-Male to Mini-B) between the RPi and radio.

Richard


 

One suggestion may be to propose a more standard connection. There are a couple of popular connection methods, one is the mini DIN on the back of some radios, the other is the kantronics 9 pin connector method and the other is the older 5 pin DIN used in many of the older packet TNC’s. The idea being that if someone could make up a batch of cables that mate up to one or more of these methods, a user can normally find packet cables for their particular radio from various sources. I know you are probably not wanting to build and sell cables but documenting this could maybe assist others who could make one for this person or maybe if the project takes off someone will start to manufacture them for this device.
The cables are already available ...

https://hammadeparts.com/shop-for-cables?olsPage=products


Brian Webster
 

Yes Bill that was my point, if his Pi project has a cable available to connect to the sound card and the header pin for the PTT control then users can buy cables such as these. The Pi project then only has to be concerned with making a cable that meets one of those standard connection methods and still able to be used with any radio.

Thank You,
Brian N2KGC

-----Original Message-----
From: RaspberryPi-4-HamRadio@groups.io [mailto:RaspberryPi-4-HamRadio@groups.io] On Behalf Of Bill Vodall
Sent: Tuesday, June 18, 2019 12:25 PM
To: RaspberryPi-4-HamRadio@groups.io
Subject: Re: [RaspberryPi-4-HamRadio] A Simple Portable Packet Station for Emergency Communications

One suggestion may be to propose a more standard connection. There are a couple of popular connection methods, one is the mini DIN on the back of some radios, the other is the kantronics 9 pin connector method and the other is the older 5 pin DIN used in many of the older packet TNC’s. The idea being that if someone could make up a batch of cables that mate up to one or more of these methods, a user can normally find packet cables for their particular radio from various sources. I know you are probably not wanting to build and sell cables but documenting this could maybe assist others who could make one for this person or maybe if the project takes off someone will start to manufacture them for this device.
The cables are already available ...

https://hammadeparts.com/shop-for-cables?olsPage=products


James French <w8iss1@...>
 

How about using this arduino nano as a kiss tnc connected between your
radio and pi:

http://www.mobilinkd.com/2014/09/11/arduino-kiss-tnc/

They also sell pre-made radio cables also that could be used.

James W8ISS

Listen for N8M from the 10th Detroit Maker Faire July 27th and 28th


Guillermo/Bill
 

Excellent project! Could you expand on the PTT part a little bit? Wich GPIO pins do you use and how do you drive them? How about a basic schematics?

73 de PY2BIL


Ronny Julian <k4rjjradio@...>
 

These guys do great work!  Best I've ever bought.  I bet they would add the RPi end of things to their inventory of "TNC Side" ends.  These guys will make up any combination needed.

On Wed, Jun 19, 2019 at 7:24 AM Brian Webster via Groups.Io <radiowebst=yahoo.com@groups.io> wrote:
Yes Bill that was my point, if his Pi project has a cable available to connect to the sound card and the header pin for the PTT control then users can buy cables such as these. The Pi project then only has to be concerned with making a cable that meets one of those standard connection methods and still able to be used with any radio.

Thank You,
Brian N2KGC


-----Original Message-----
From: RaspberryPi-4-HamRadio@groups.io [mailto:RaspberryPi-4-HamRadio@groups.io] On Behalf Of Bill Vodall
Sent: Tuesday, June 18, 2019 12:25 PM
To: RaspberryPi-4-HamRadio@groups.io
Subject: Re: [RaspberryPi-4-HamRadio] A Simple Portable Packet Station for Emergency Communications

> One suggestion may be to propose a more standard connection. There are a couple of popular connection methods, one is the mini DIN on the back of some radios, the other is the kantronics 9 pin connector method and the other is the older 5 pin DIN used in many of the older packet TNC’s. The idea being that if someone could make up a batch of cables that mate up to one or more of these methods, a user can normally find packet cables for their particular radio from various sources. I know you are probably not wanting to build and sell cables but documenting this could maybe assist others who could make one for this person or maybe if the project takes off someone will start to manufacture them for this device.

>>>

The cables are already available ...

  https://hammadeparts.com/shop-for-cables?olsPage=products







Richard Bates
 

On Wed, Jun 19, 2019 at 08:18 PM, Guillermo/Bill wrote:
Could you expand on the PTT part a little bit?
The DireWolf manual,  section 9.2.8.3, page 66, explains the addition you need in the direwolf.conf file, for example to use GPIO 26 you want

PTT GPIO 26

i.e. in this example, GPIO26 (pin #37) will go "high" when the software TNC wants to transmit.

This small reed relay fits conveniently inside the RPi case, and can be soldered directly to to GPIO line.

You can see that:
 - relay pin 1 connects to the radio PTT line
 - relay pin 2 connects to the GPIO line, pin 37 in this example
 - relay pins 3 and 4 connect to ground, for example pin 39

As I didn't need the functionality of the built-in RPi audio, I choose to disconnect the RPi audio-out lines from the built-in mini-jack, by breaking the tracks - so I could use it for the PTT line (relay pin 1).


You could alternatively simply add a mini-jack to the RPi case and take the PTT signal out that way.

Richard
 


David Ranch <dranch@...>
 


Hello RIchard,

Your solution seems overly complex but maybe I'm missing something:

   - Why use a relay with a higher delay time compared to just using a simple transistor circuit with lower delays?

   - Why do all the complex tapping into the onboard output-only soundcard when you still need a soundcard input?  Why not just do everything on the external sound device (input and output)?

--David


On 06/20/2019 08:04 AM, Richard Bates wrote:
On Wed, Jun 19, 2019 at 08:18 PM, Guillermo/Bill wrote:
Could you expand on the PTT part a little bit?
The DireWolf manual,  section 9.2.8.3, page 66, explains the addition you need in the direwolf.conf file, for example to use GPIO 26 you want

PTT GPIO 26

i.e. in this example, GPIO26 (pin #37) will go "high" when the software TNC wants to transmit.

This small reed relay fits conveniently inside the RPi case, and can be soldered directly to to GPIO line.

You can see that:
 - relay pin 1 connects to the radio PTT line
 - relay pin 2 connects to the GPIO line, pin 37 in this example
 - relay pins 3 and 4 connect to ground, for example pin 39

As I didn't need the functionality of the built-in RPi audio, I choose to disconnect the RPi audio-out lines from the built-in mini-jack, by breaking the tracks - so I could use it for the PTT line (relay pin 1).


You could alternatively simply add a mini-jack to the RPi case and take the PTT signal out that way.

Richard


 

Technical documentation for DRAWS™ -- includes schematic, pinout, etc.

GPIO 12 and GPIO 23 provide PTT through the left and right DIN-6 connectors (amateur packet radio standard to radios).  DRAWS™ provides 2 multi-speed packet (300/1200/9600/...) Direwolf modems through these connections.

No soldering required, no hacking sound fobs, etc.   Raw HAT, self assemble kit, and pre-built units.

On Tue, Jun 18, 2019 at 5:45 AM Ronny Julian <k4rjjradio@...> wrote:
I like it except for the soldering.  Not exactly appliance compliant.  My vision will not let me do the soldering.
John D. Hays
Kingston, WA
K7VE

 


Richard Bates
 

David

 - relay vs transistor - largely because I had a relay at hand - I didn't feel the delay difference was significant, compared to the 300ms Tx delay set in the TNC - also the relay ensured a clean short to ground - but I agree, a transistor would be fine

 - as to using the existing mini-jack - it was easier than making another hole in the RPi case - I didn't care about the RPi built-in audio-out, as I was using the USB sound adapter for both audio in & out

So - both just my choice - but I don't claim either are significant to the overall idea.

Richard


Richard Bates
 

I think we're just comparing time vs money - my project took a little more tinkering but I saved $149.95. I acknowledge of course that the DRAWS card offers many other features, beyond what this simple project requires.


 

Richard,

A very valid point.  The DRAWS™ HAT integrates a lot of functionality and is purpose built for the applications that use it.  Certainly one can build everything it offers, cheaper, given time and skill.  I was noting the 'no solder' desire and I fall largely into that category, especially for very small parts.  (I have monocular vision, so no depth perception and my good eye is aging).  I do solder slightly larger and less critical stuff :)

The observation is that when you take your DIY project to the club meeting, you will get a lot of "That's cool, can you make one for me?"


On Thu, Jun 20, 2019 at 10:41 AM Richard Bates <richard@...> wrote:
I think we're just comparing time vs money - my project took a little more tinkering but I saved $149.95. I acknowledge of course that the DRAWS card offers many other features, beyond what this simple project requires.

--
John D. Hays
Kingston, WA
K7VE

 


Guillermo/Bill
 

Thanks Richard for your detailed explanation! This is looking really interesting and I might tackle that project too. 
I'm looking into the other comments on this thread and see other interesting ideas too. DRAWS is a little too much for me now, but I have already a product from NW and they seem to make good stuff.

Thanks again 
73 from PY2BIL