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Re: Raspberry Pi Zero APRS Transmitter needs a PA stage!

nick klinger
 


Raspberry Pi Zero APRS Transmitter needs a PA stage!

Mike
 

I managed to get a Raspberry Pi Zero W to function as an APRS transmitter.  Now I'm looking for a simple power amplifier (PA) stage that would boost the Pi's signal to around 500mw or so. I can't use a heavy, pre-built amplifier "brick", because I intend to use this transmitter on a high altitude balloon (HAB) project, so power consumption and payload weigh are of primary concern.

I would really appreciate any links to a modern, simple, 500mw (or so) discrete-component-style 2 meter FM power amplifier that I can  wire up "dead bug" style (aka components wired in the air to each other!).  It would be really nice to have all components be inexpensive and readily available, so that others can easily replicate this circuit without running into supply-chain issues.

Any suggestions would be very much appreciated!


FOR THE CURIOUS on how I got the Pi to transmit APRS packets -
-------------------------------------------------------------------------------------
I started with the "pifm" github repository and tweaked that code to get the transmitter working both in NBFM mode, and onto the USA 2 meter Packet/APRS frequency of 144.390 Mhz.  I use some command-line tools from the direwolf APRS codebase to encode APRS packets (which include the Pi's current GPS position) and generate an audio wav file containing modulated audio.  I then "play" that file using the modified pifm codebase, which transmits the audio over 2 meter FM, which a packet/APRS receiver can successfully decode.

P.S. Once I get the APRS transmitter to be clean and "useful" I'll try adding an RTL-SDR dongle to the setup and have a full-fledged APRS transceiver on a Pi Zero W!

'73
- Mike
  KA9CQL
  Victorville, CA, USA


Re: Have lost my Davis VantageVue

Al Massaro KF5SMH
 

Thanks for that tidbit of information.
AL M
KF5SMH


Re: Have lost my Davis VantageVue

g4sra
 

Do what any 12 year old child learning the Pi would do....start here

https://www.raspberrypi.org/magpi-issues/

with Issue MagPi01.pdf

On 23/02/18 15:13, Al Massaro wrote:
Thank You very much, this is what has me at my wits end at times, writing commands for Linux. I do not understand what has to be in the command line to get to the correct file or folder. I never know if I need pi, home, weewx or whatever prior to the file or function I am trying to access.
Again Thank You,
AL M
KF5SMH


Re: Have lost my Davis VantageVue

Steve McGrane <temporarilyoffline@...>
 

You got it!

On Fri, Feb 23, 2018 at 10:24 AM, Al Massaro <almassaro@q.com> wrote:
Steve, Oh man, Thank You for that, I did not know I wanted or needed that, but that explains a lot! So if I have this correct to look at spec_helper.rb the command would look like;
cat test/serverspec/spec_helper.rb 
I am doing all of this in Debian on an RPI 2B via LX Terminal.
So I do not take up a bunch of space here if you would prefer my contact email is kf5smhwx@q.com
Thank you again!!
AL M
KF5SMH



Re: Have lost my Davis VantageVue

Al Massaro KF5SMH
 

Steve, Oh man, Thank You for that, I did not know I wanted or needed that, but that explains a lot! So if I have this correct to look at spec_helper.rb the command would look like;
cat test/serverspec/spec_helper.rb 
I am doing all of this in Debian on an RPI 2B via LX Terminal.
So I do not take up a bunch of space here if you would prefer my contact email is kf5smhwx@q.com
Thank you again!!
AL M
KF5SMH


Re: Have lost my Davis VantageVue

Steve McGrane <temporarilyoffline@...>
 

the tree and pwd commands might be of help.

`pwd` is for "print working directory" and this will show you your current path... like `/home/pi` or `/var/log`

Next is tree

Run `sudo apt-get install tree -y`

This will give you a tool that will help you visually see the folders you are working on.

At any time, you can run `tree` from the command line to see where you are.

± tree
.
├── README.md
├── deploy.yml
├── site
│   └── master.tar.gz
├── templates
│   ├── Constant.php.j2
├── test
│   └── integration
│       └── default
│           └── serverspec
│               ├── default_spec.rb
│               └── spec_helper.rb
└── vault
    ├── vars.yml
    └── vault.yml


Here you can see a simple layout of the folders you are working with.

from the diagram above, if I wanted to see the contents of the vault, I would type:

cat vault/vault.yml

(cat displays the contents of the file located at vault/vault.yml)

Hopefully that helps some.

What OS do you use most often? (Windows/OSX/?)


On Fri, Feb 23, 2018 at 9:13 AM, Al Massaro <almassaro@q.com> wrote:
Thank You very much, this is what has me at my wits end at times, writing commands for Linux. I do not understand what has to be in the command line to get to the correct file or folder. I never know if I need pi, home, weewx or whatever prior to the file or function I am trying to access.
Again Thank You,
AL M
KF5SMH



Re: Have lost my Davis VantageVue

Al Massaro KF5SMH
 

Thank You very much, this is what has me at my wits end at times, writing commands for Linux. I do not understand what has to be in the command line to get to the correct file or folder. I never know if I need pi, home, weewx or whatever prior to the file or function I am trying to access.
Again Thank You,
AL M
KF5SMH


Re: Have lost my Davis VantageVue

g4sra
 

On 22/02/18 22:59, Al Massaro wrote:
....I ran your suggestion in the terminal window and it came back invalid option '/' "try ls --help".
....I would love to know what, or why I did not get a listing back, if I did something wrong or typed it in incorrectly.
You most likely typed

ls -lrt/dev

instead of

ls -lrt /dev


Re: R Pi and Alexa - for Amateur Radio

Steve, KB9MWR
 

I use the two-tone detect Pi image:
http://www.twotonedetect.net/twotonedetect-pi-image/
That is setup to spawn a recording that is then sent to google's API.


Re: Have lost my Davis VantageVue

 

Here's a starting point -- it's technical, but you can lock a USB to an ID  https://unix.stackexchange.com/questions/66901/how-to-bind-usb-device-under-a-static-name

On Thu, Feb 22, 2018 at 1:23 PM, Michael Dunn <ml000-0013@...> wrote:
  Hi Al,

While I don't have WeeWx or a Davis weather station, I have a similar setup using rtl_433 to push weather to APRS.FI.  I would guess that the USB device you use to connect to the weather station has been re-enumerated.  Try this: unplug your connection to the USB weather device.  Then plug it back in and run 'ls -lrt /dev' on the Pi; one of the last devices in the output will likely be the USB device that you should configure in WeeWx.

  Cheers
  Mike




--


John D. Hays
Edmonds, WA
K7VE

   


Re: Have lost my Davis VantageVue

Al Massaro KF5SMH
 

I found that I was experiencing some router issues also while troubleshooting. I did a firmware upgrade on my router and I am now reporting to APRS, but just to try and learn something I ran your suggestion in the terminal window and it came back invalid option '/' "try ls --help". I did and it came back with a list of short argument options.
Thanks for the reply and help. I would love to know what, or why I did not get a listing back, if I did something wrong or typed it in incorrectly.
Thanks again
AL M
KF5SMH


Re: Have lost my Davis VantageVue

Michael Dunn
 

  Hi Al,

While I don't have WeeWx or a Davis weather station, I have a similar setup using rtl_433 to push weather to APRS.FI.  I would guess that the USB device you use to connect to the weather station has been re-enumerated.  Try this: unplug your connection to the USB weather device.  Then plug it back in and run 'ls -lrt /dev' on the Pi; one of the last devices in the output will likely be the USB device that you should configure in WeeWx.

  Cheers
  Mike


Have lost my Davis VantageVue

Al Massaro KF5SMH
 

I have an RPI 2b running DRATS, and WeeWx reporting to APRS.FI. I did some rearranging of the computer area and lost my upload to APRS. The Pi shows the bridge connection as bus001 device006. WeeWx shows that the usb port should be USB0 or USB1, the unit was working just fine up to the unplug. I have run the stop and start commands a number of times to no avail, I am not a LINUX wiz so not sure how to find problem, or what to do once I do. 
Somebody got a compass to point me in the right direction?
AL M
KF5SMH


Re: R Pi and Alexa - for Amateur Radio

Bill Diaz
 

Guys,
    I am experimenting with remote operating using 2 Echo Dots for audio,  with a Raspberry Pi running PiHpSDR and RealVNC, connected to an Apache Labs 100D. The remote end currently uses a Surface Pro 4 running RealVNC client.  Seems to work ok, but more testing needed.

    The Echo Dots use the Alexa "Drop in" feature to establish a two way audio connection.  The station end has the receiver speaker closely coupled to the Station Echo Dot, and the 3.5mm TRS output jack of the Dot is connected to the mic input of the 100D.  Latency appears to be somewhat variable, likely due to the load on the Amazon Servers.   Not perfect, but this should work with voice audio and any transceiver with external audio connection capability.

   Don't know if I can attach drawings here, but attached a drawing showing how it all works.

Bill KC9XG

On 2/22/2018 11:33 AM, Steve KB9MWR via Groups.Io wrote:
Back in 2012 I did some ham radio stuff with ASR (automatic speech recognition) at that time Alexa didn't exist that I know of, so I did it with Googles API.

http://kb9mwr.blogspot.com/2012/02/ham-radio-voice-recognition.html

I still have a Raspberry Pi that is listens for two-tone fire and EMS pages. And when that happens the next few seconds of audio are submitted to Googles ASR API and the transcript is logged to file and sent to me as a text message of the call.

Honestly I haven't looked into if there is an API for Alexa or if you have to use their hardware.




Re: R Pi and Alexa - for Amateur Radio

 

On Thu, Feb 22, 2018 at 10:09 AM, Kevin Elliott <kevin@...> wrote:
Steve,

> I still have a Raspberry Pi that is listens for two-tone fire and EMS pages.  And when that happens the next few seconds of audio are submitted to Googles ASR API and the transcript is logged to file and sent to me as a text message of the call.

How cool. Can you share implementation details for this? I’d love to set that up.

Kevin
KK6NHN





--


John D. Hays
Edmonds, WA
K7VE

   


Re: R Pi and Alexa - for Amateur Radio

Kevin Elliott
 

Steve,

I still have a Raspberry Pi that is listens for two-tone fire and EMS pages. And when that happens the next few seconds of audio are submitted to Googles ASR API and the transcript is logged to file and sent to me as a text message of the call.
How cool. Can you share implementation details for this? I’d love to set that up.

Kevin
KK6NHN


Re: R Pi and Alexa - for Amateur Radio

 

On Thu, Feb 22, 2018 at 9:33 AM, Steve KB9MWR via Groups.Io <kb9mwr@...> wrote:
Back in 2012 I did some ham radio stuff with ASR (automatic speech recognition)  at that time Alexa didn't exist that I know of, so I did it with Googles API.

http://kb9mwr.blogspot.com/2012/02/ham-radio-voice-recognition.html

I still have a Raspberry Pi that is listens for two-tone fire and EMS pages.  And when that happens the next few seconds of audio are submitted to Googles ASR API and the transcript is logged to file and sent to me as a text message of the call.

Honestly I haven't looked into if there is an API for Alexa or if you have to use their hardware.







--


John D. Hays
Edmonds, WA
K7VE

   


Re: R Pi and Alexa - for Amateur Radio

Steve, KB9MWR
 

Back in 2012 I did some ham radio stuff with ASR (automatic speech recognition) at that time Alexa didn't exist that I know of, so I did it with Googles API.

http://kb9mwr.blogspot.com/2012/02/ham-radio-voice-recognition.html

I still have a Raspberry Pi that is listens for two-tone fire and EMS pages. And when that happens the next few seconds of audio are submitted to Googles ASR API and the transcript is logged to file and sent to me as a text message of the call.

Honestly I haven't looked into if there is an API for Alexa or if you have to use their hardware.


Re: Will we see a Pi 4 in the near future...?

Steve McGrane <temporarilyoffline@...>
 

They're actually cheaper accounting for inflation ;-). I have a '66 in good running condition that I got for $5k.  You can find some "well worn" examples in the hundreds or even free if you look around a bit.

On Thu, Feb 22, 2018 at 10:01 AM, Lawrence Macionski via Groups.Io <am_fm_radio@...> wrote:
Can you still buy VW Beetles for 1967 $1995 prices??


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