SDR (Software Defined Radio) with TX

In Stock:
BladeRF USD $420 – $650
USRP B200 USD $700?
LimeSDR USD $299

ADALM-PLUTO: A New $149 TX Capable SDR with 325 – 3800 MHz Range, 12-Bit ADC and 20 MHz Bandwidth
LimeSDR Mini
up/down-convert 10 GHz
LMS8001 Companion
Raspberry Pi + Rpitx + low pass filter as TX, RTL-SDR Dongle as RX
Transmitting FM, AM, SSB, SSTV and FSQ with just a Raspberry Pi

Digital Television Transmitter on Raspberry Pi:
GPIO -> QPSK (!)
Digital Television Transmitter on Raspberry Pi (GitHub)

How To: Battery powered Passive POE for Ubiquiti device

Ubiquiti device POE specifications: 10.5V ~ 25V DC

Network port pin out:
Pairs 4, 5 (+)
7, 8 (-)

For 100M device:
Use pin 4, 5 as +, pin 7, 8 as -.

For 1000M (1G) Device
We need transformers pass through data and inject power.

Plan A:
Li-ion battery x2 , 8.4V – 6V. DC-DC step-up to 14V (double volt)

Plan B:
Li-ion battery x3 , 12.6V – 9V. DC-DC step-up to 21V (double volt)

Plan C:
Lead battery x1 ,12V. DC-DC step-up to 24V (double volt)

24v passive POE power Injector:
Plan A:
ER-X SFP Gigabit POE port x5
Plan B:
千兆POE供电器 POE分离器 Gigabit Passive PoE PSI348G

to do:
ESD – Transient Voltage Suppression Diodes (TVS)
Lightning Surge
PTC Polyfuse 1.25A

gas tubes, reverse diodes and MOVs?
2018 Aug 28 update:

802.3at/af :
TL-SG1005P 5 port 1000M switch (53.5V DC 1.13A input)
Single Port max 30W, Switch Max 57W.
$289 CNY

power over ethernet tutorial


Waterproof Ethernet Surge Protector High PoE+/ESD Gigabit 1000Mbs – Thunder/Lighting Outdoor Protection

Bourns Power over Ethernet (PoE) Surge Protection

Littelfuse : Circuit protection of IP-networked security camera systems

Protecting PoE Syste ms from Lightning and Other Electrical Hazards


Gigabit Passive PoE injector power over ethernet


Linux : decode APRS packet from RTL SDR

SDR (rtl_fm) -> APRS Packet Decoder (multimon-ng) -> Network Sent APRS data (socat)
Rtl_fm Guide

multimon-ng @ github
Command (copy from source code!)

Usage: %s [file] [file] [file] ...
If no [file] is given, input will be read from your default sound
hardware. A filename of \-\ denotes standard input.
-t : Input file type (any other type than raw requires sox)
-a : Add demodulator
-s : Subtract demodulator
-c : Remove all demodulators (must be added with -a )
-q : Quiet
-v : Level of verbosity (e.g. '-v 3')
For POCSAG and MORSE_CW '-v1' prints decoding statistics.
-h : This help
-A : APRS mode (TNC2 text output)
-m : Mute SoX warnings
-r : Call SoX in repeatable mode (e.g. fixed random seed for dithering)
-n : Don't flush stdout, increases performance.
-e : POCSAG: Hide empty messages.
-u : POCSAG: Heuristically prune unlikely decodes.
-i : POCSAG: Inverts the input samples. Try this if decoding fails.
-p : POCSAG: Show partially received messages.
-f : POCSAG: Disables auto-detection and forces decoding of data as
( can be 'numeric', 'alpha' and 'skyper')
-b : POCSAG: BCH bit error correction level. Set 0 to disable, default is 2.
Lower levels increase performance and lower false positives.
-o : CW: Set threshold for dit detection (default: 500)
-d : CW: Dit length in ms (default: 50)
-g : CW: Gap length in ms (default: 50)
-x : CW: Disable auto threshold detection
-y : CW: Disable auto timing detection
Raw input requires one channel, 16 bit, signed integer (platform-native)
samples at the demodulator's input sampling rate, which is
usually 22050 Hz. Raw input is assumed and required if piped input is used.;


APRS iGate Expample:
APRS RX iGate z tunera DVB-T (RTLSDR) (Cubieboard , in Polish)

SDR Command (need test):
Decode to display in screen:

rtl_fm -f 144.64M -s 22050 - | multimon-ng -a AFSK1200 -a FSK9600 -A -t raw /dev/stdin

rtl_fm :
-f 144.64M //Frequency to tune to 144.64 mHz
-s 22050 //means to sample the radio at 22050 times/sec
-a AFSK1200 //add demodulator AFSK1200
-a FSK9600 //add demodulator FSK9600
-A //APRS mode (TNC2 text output)
-t raw /dev/stdin //Input file type raw from system stand input (?)

nRF24L01 for Arduino

Arduino 需要無線電傳數據的話, nRF24L01+ 的確是首選.
在 2.4GHz 工作, 不用牌照. 而且一套兩隻約 $2 USD左右, 很平.

nRF24L01 是舊版, 巳停產.
可以的話找 nRF24L01+ 最好.

RF24 – NRF24L01 Driver
RF24 writer’s blog
arduino leonardo 的 SPI 接線方法和其它的有點不一樣, 詳見:
arduino leonardo 與 nRF24L01 連接方法

Step by Step:
1. 在 Arduino SDK 安裝好 “libraries”,
2. Re-Start Arduino SDK
3. 打開 GettingStarted.pde.
4. Upload 到兩套 Arduino 內
5. 兩套Arduino 同時接到 PC , 打開兩個 Com Mon
6. 在其中一個 Com Mon 輸入 “T” (設定為發送信息)
7. Done!

APRS: Automatic Position Reporting System


2010版 AVRT2台機專用型APRS收發設備 $350 CNY
國產精制OpenTracker+(OT+)套件 $158 CNY
OpenTracker+ SMT

arduino-aprs with beRTOS
Trackuino:The Arduino APRS tracker
WhereAVR: Low-cost APRS tracker (Atmega8)

ATmega-TNC. An ATmega8 based UI TNC.
10Mbps TNC – S53MV