RF.Guru Analog Hotspot 70CM (UHF) 500mW Power
RF.Guru Analog Hotspot 2M (VHF) 500mW Power
RF.Guru Analog Transceiver 70CM (UHF) 1.3W Power (added a Low Pass filter) needs additinal power best used with an external power source like RF.Guru Pi Zero PSU
RF.Guru Analog Transceiver 2M (VHF) 1.3W Power (added a Low Pass filter) needs additinal power best used with an external power source like RF.Guru Pi Zero PSU
Used PIN's:
- 3 GPIO2
- 6 GPIO3
- 35 GPIO19
- 8 TX
- 10 RX
- 12 CLK
- 32 GPIO12 -> COS input from the radio chip
- 36 GPIO16 -> PTT pin
- 38 GPIO20
- 40 GPIO2
These boards are also suitable for conducting analog ham radio experiments within the 70cm and 2m ham radio frequency bands. (Like APRS iGate/Digipeater, packet etc...)
The hotspot is not suitable for connecting an outdoor antenna because it lacks a sufficient low-pass filter. However, the transceiver version is equipped with a low-pass filter and is suitable for transmitting via an outdoor antenna.
The RF 50 ohm output requires an antenna with a SWR (Standing Wave Ratio) of less than 4:1, which is considered reasonable. If you experience sound distortion, it could indicate that the antenna being used has a high SWR, leading to common-mode currents that may affect the RF chip. To test, use a 50-ohm dummy load (for UHF) and consider using a more suitable antenna. We recommend and sell antennas that work without any issues.
- UBS1/2 is only rated for 0.5Amps ... so do not connect the hotspot to such port on your computer/laptop ... it will porpably not work !
- USB3 port (blue connector) has enough power (0.9Amps) to drive the hotspot !
If you prefer to handle everything manually, you can find the necessary resources here:
- RF Module (SA818) can be programmed via https://github.com/Guru-RF/SA818.
- The I2C audio chip kernel module can be found here https://github.com/waveshare/WM8960-Audio-HAT.
Bookworm Image 2024-09-09 (only for Raspberry Pi Zero 2W, Raspberry Pi 4 and Raspberry Pi 5)
The firmware version released on 2024-09-09 now handles CTCSS decoding through software. Previously, some users encountered a significant bug in the FM chip’s CTCSS decoding, leading to random false detections. If you’re using an earlier version, we strongly recommend upgrading!
This firmware now includes talk group mapping to CTCSS tones, making it much easier to switch between talk groups. It also works for radios without DTMF macros! The TX CTCSS tone remains fixed across all talk groups, while the RX tone is variable and can be configured through the mapping settings in the configurator, the TX tone (fixed for all talkgroups) is also configurable in the configurator.
Utilize PI-Imager to write the image to your MicroSD card! Don't use svxlink or svxspot as a username, these are system usernames, using them will result in a broken installation !
You can set username/password and wifi credentials in the Raspberry PI Imager tool ... there is no default username/password !
Use the latest release of PI-Imager Github
Youtube demonstration of how to use PI-Imager on Windows 11
Youtube demonstration of how to use PI-Imager on MacOS X
Boot the hotspot with a descent power supply that can provide enough current and has a stable voltage > 5v !
It appears that the Raspberry Pi freezes after resizing the file system. Currently, after the initial boot, wait for 10 minutes, disconnect the power, and then restart. We suspect this issue is a bug and anticipate it will likely be resolved in a future release of pi-shrink.
To complete the final configuration step, you can connect via the dashboard by browsing to your hotspots ip (http://). Chooce shell for shell access !
Once logged in, you can execute:
sudo hotspot-configas illustrated in this video:
hostspot-config2.mp4
The chip has a 5 kHz deviation. For the best audio experience, transmit using Wide FM (FM) – it will sound much better, and so will you!
To activate a talkgroup, send the corresponding CTCSS tone from the mapping while in TG0.
- You’ll hear a bleep tone 15 seconds after a QSO.
- This will instantly open the talkgroup – no need for double presses like before.
- You can start speaking immediately!
To get the current IP address of the hotspot, send: DTMF D911#
To set up multiple talkgroups for monitoring, configure them in the hotspot-config using this format: 8++, 23+, 50, 51, 52, 53, 54, 55
- The TX CTCSS tone remains the same across all talkgroups.
- The plus signs (+) indicate priority levels.
Temporarily Monitor a Talkgroup:
To temporarily monitor another talkgroup, send: DTMF 94#
For example, to monitor TG23: 9423#
You can map talkgroups via CTCSS tones using the following format: tone:talkgroup, tone:talkgroup, …
Example Default Mapping:
67.0:8400, 69.3:8, 71.9:23, 74.4:9000, 77.0:50, 79.7:51, 82.5:52, 85.4:53, 88.5:54, 91.5:55
Mapping a Single Default Talkgroup:
If you want only one default talkgroup or plan to switch via DTMF or the portal, map it like this: 88.5:8
This maps CTCSS tone 88.5 to talkgroup 8.
The hotspot also has a local portal. You can access it:
- Via its hostname (if your network supports it).
- Or directly via its IP address.
For adding additional (wifi) networks you can use the
sudo nmtui provided by the Pi OS.
Do not remove AccessPopup !! It takes about 2 minutes to switch from WiFi network ... so please be patient !
Avoid configuring static IPs on the WiFi, as it can disrupt the operation of Accesspopup.
We advice a frequency not in use by nearby repeaters, also do not use ISM frequency 433Mhz ... we use 439.100 on 70cm and 145.250 on 2m
For CTCSS tone ... use a tone not localy used ... we use 88.5
Edit the following file for base talkgroups:
sudo vi /var/www/html/include/tgdb.phpEdit the following file for talkgroup buttons:
sudo vi /var/www/html/include/config.inc.phpaccesspopup is installed by default, if no WiFi network is reachable it will automaticaly presents itselves as an acccess point where you can connect to.
SSID Accesspopup with passwd 1234567890 Default IP Hotspot in AccessPopup is http://192.168.50.5/
When switching networks (without reboot) it can take up to 2 minutes for the pi to reconnect to a known network ! 2 minutes is quite long ... so please have patience !!!
Avoid configuring static IPs on the WiFi, as it can disrupt the operation of Accesspopup !
To disable accesspupup
sudo systemctl disable AccessPopup.timer
sudo rebootTo re-enable accesspup
sudo systemctl enable AccessPopup.timer
sudo rebootYou need to go to Personal Hotspot setting until the hotspot is connected, there is no option on the iPhone/iPad to have the SSID beeing broadcasted all the time. Once connected it works like a charm.
hotspot.mp4
(not needed when using the image, this is preinstalled on the image)
Prepare your sd-card with Raspberry PI OS (Bookworm 32Bit Lite) (Youtube)
Login to your system with ssh add run following commands:
sudo apt -y install gitgit clone https://github.com/Guru-RF/SVXSpot.gitcd SVXSpot
sudo bash install-radiomodule.shcd SVXSpot
sudo bash install-svxlink.sh(modify /usr/sbin/hotspot_volume to the desired volume)
systemctl stop svxlink
/sbin/hotspot_volume
arecord -V stereo -r 44100 -f S16_LE -c 2 /dev/null(modify /usr/sbin/hotspot for rf module changes)
Sending D1# dtmf on the configured frequency starts the parrot.
(On Anytone DTMF ABCD -> P1 = A P2 =B up button =C down button =D)
curl -L -o - https://raw.githubusercontent.com/Guru-RF/SVXSpot/master/test-hotspot.sh | sudo bash