Modems

The Paparazzi autopilot features a 5V tolerant 3V TTL serial port to interface with any common radio modem. The bidirectional link provides real-time telemetry and in-flight tuning and navigation commands. The system is also capable overlaying the appropriate protocols to communicate thru non-transparent devices such as the Coronis Wavecard or Maxstream API-enabled products, allowing for hardware addressing for multiple aircraft or future enhancements such as data-relaying, inter-aircraft communication, RSSI signal monitoring and automatic in-flight modem power adjustment. Below is a list of some of the common modems used with Paparazzi, for details on configuring your modem see the Airframe Configuration page.

Maxstream XBee Pro

These relatively cheap and light modules implement the ZigBee/IEEE 802.15.4 norm. They allow up to 1 mile range(Paparazzi tested to 2.5km). The main drawback of using such 2.4Ghz modules for datalink is that it will interfere with the 2.4Ghz analog video transmitters and a inevitable decrease in range when in proximity to any wifi devices.

XBee Pro USB Stand-alone Modem (XBP24-PKC-001-UA)

Frequency Band 2.4Ghz Output Power 100mW (Xbee Pro) Sensitivity -100 dBm RF Data Rate Up to 250 Kbps Interface data rate Up to 115.2 Kbps Power Draw (typical) 214 mA TX / 55 mA RX Supply Voltage 3.3v Range (typical, depends on antenna & environment) Up to 1500m line-of-sight Dimensions 24 x 33mm Weight 4 grams Interface 20-pin mini connector Chip antenna, ¼ monopole integrated whip antenna or a U.FL antenna connector (3 versions) price : ~32$

XBee Pro OEM Modem

Pinout

Maxstream XBee pinout

3.3v

1
	(Red)
2	DOUT	TX output	(Green)
3	DIN	RX input	(Blue)
10	GND		(Black)

Documentation

• product page
• datasheet
• user manual

Maxstream 9XTend

These larger units have been tested on the 900Mhz band, but are also available in 2.4Ghz. They are a bit on the heavy side(~20grams) but give good performance at range. They have adjustable power settings from 100mW to 1W. Testing has shown range up to 2 miles with 100mW.

9XTend USB Modem

Frequency Band 900Mhz and 2.4Ghz (2 versions) Output Power 1mW to 1W software selectable Sensitivity -110 dBm (@ 9600 bps) RF Data Rate 9.6 or 115.2 Kbps Interface data rate up to 230.4 Kbps Power Draw (typical) 730 mA TX / 80 mA RX Supply Voltage 2.8 to 5.5v Range (typical, depends on antenna & environment) Up to 64km line-of-sight Dimensions 36 x 60 x 5mm Weight 18 grams Interface 20-pin mini connector RF connector RPSMA (Reverse-polarity SMA) or MMCX (2 versions) price : ~179$

9XTend OEM Modem

Pinout

Maxstream 9XTend Pinout

9XTend 20-pin Header	Name	Tiny Serial-1 Header	Notes
1	GND	1 (GND)	Ground
2	VCC	N/A (requires 5V)	5V power (150mA - 730mA Supplied from servo bus or other 5V source)
5	RX	8 (TX)	3-5V TTL data input - connect to Tiny TX
6	TX	7 (RX)	5V TTL data output - connect to Tiny RX
7	Shutdown	N/A (requires 5V)	Permanently connect this pin to the 5V bus for normal operation

Notes:

• 9XTend can run on voltages as low as 2.8V but users are strongly advised against connecting any modem (especially high power models) to the sensitive 3.3V bus supplying the autopilot processor and sensors.

Documentation

• product page
• datasheet
• user manual

Aerocomm

Aerocomm's API mode is not yet implemented. Therefore they are used in transparent mode. Users are reporting these modems cause more interference with GPS reception then the Maxstream modem.

AC4868-250 Frequency Band 868MHz (For Europe). Output Power (w/ 2dBi antenna) 250 mW Sensitivity (@ full RF data rate) -103 dB RF Data Rate Up to 28.8 Kbps INterface Data Rate Up to 57.6 Kbps Power Draw (typical) 240 mA TX / 36 mA RX Supply Voltage 3.3v & 5V or 3.3v only Range (typical, depends on antenna & environment) Up to 15 kilometers line-of-sight Dimensions 49 x 42 x 5mm Weight < 21 grams Interface 20-pin mini connector Antenna MMCX jack Connector price : ~80$	Aerocomm USB Stand-alone Modem
AC4790-200 Frequency 902-928MHz (North America, Australia, etc). Output Power 5-200mW Sensitivity (@ full RF data rate) -110dB RF Data Rate up to 76.8 Kbps INterface Data Rate Up to Up to 115.2 Kbps Power Draw (typical) 68 mA Supply Voltage 3.3v & 5.5V Range (typical, depends on antenna & environment) Up to 6.4 kilometers line-of-sight Dimensions 42 x 48 x 5mm Weight < 20 grams Interface 20-pin mini connector Antenna MMCX jack Connector or internal price : ~80$	AC4868 OEM Modem
AC4790-1000 Frequency 902-928MHz (North America, Australia, etc). Output Power 5-1000mW Sensitivity (@ full RF data rate) -99dB RF Data Rate up to 76.8 Kbps INterface Data Rate Up to Up to 115.2 Kbps Power Draw (typical) 650 mA Supply Voltage 3.3V only Range (typical, depends on antenna & environment) Up to 32 kilometers with high-gain antenna Dimensions 42 x 48 x 5mm Weight < 20 grams Interface 20-pin mini connector Antenna MMCX jack Connector price : ~80$

Pinout

Aerocomm AC4868 modem pinout

Aerocomm AC4490 wiring example

Wiring the Aerocomm AC4868 to the Tiny

AC4868 20-pin Header	Name	Color	Tiny Serial-1	Notes
2	Tx	green	7	(Note 1)
3	Rx	blue	8	(Note 1)
5	GND	black	1	-
10+11	VCC	red	2	+3.3v
17	C/D	white	3	Low = Command High = Data

Note 1 : names are specified with respect to the AEROCOMM module

Documentation

• AC4790 product page
• AC4790 Datasheet
• AC4790 Manual
• AC4848 product page
• AC4868 Datasheet
• AC4868 user manual

Radiotronix

These Radiotronix modems are used in transparent mode. Use the WI232EUR Evaluation Software for configuring the modems for the set speed. Connect /CMD and CTS for programming. The DTS version for the US market might cause severe interference with GPS reception, it is not recommended.

WI232EUR Frequency Band 868MHz (for Europe) Output Power 32 mW RF Data Rate Up to 76.8 kbps Interface Data Rate up to 115.2 kbps Power Draw (typical) 65 mA TX / 20 mA RX Supply Voltage 3.3v Range (typical, depends on antenna & environment) 500 meters line-of-sight Dimensions 24 x 21 x 4mm Weight ~2 grams Interface solder connector Antenna solder connector price : ~25$

WI232EUR Modem

Pinout Wiring the WI232EUR to the Tiny WI232 pins Name Tiny Serial-1 Notes 6 TxD 7 (Note 1) 5 RxD 8 (Note 1) 15-18 GND 1 - 19 VCC 2 +3.3v 4 /CMD - (Note 2) 7 CTS - (Note 3) Note 1 : names are specified with respect to the Radiotronix module Note 2 : connect to RTS to program device with Evaluation software Note 3 : connect to CTS to program device with Evaluation software Documentation WI232EUR data sheet WI232EUR user's manual Evaluation software Coronis WaveCard These relatively inexpensive and light modules implement a Coronis proprietary protocol. Low power consumption - high latency - I would not recommend these modules mostly because of the low quality of the distribution and support. The documentation is rather poor and not easily available. Frequency Band 400MHz, 868Mhz and 915MHz (3 versions) Output Power 25mW and 500mW (2 versions) Sensitivity -110 dBm (@ 9600 bps) Data Rate 100 Kbps Power Draw (typical) 45mA (25mW), 450mA (500mW) TX / 15 mA RX Supply Voltage ... Range (typical, depends on antenna & environment) Up to 1km (25mW) , 5km (500mW) line-of-sight Dimensions 30 x 28 x 7mm (25mW), 37 x 30 x 7mm (500mW) 50 ohm RF port for antenna connection Documentation www.coronis-systems.com Wavecard datasheet Video Transmitter Telemetry 2.4GHz Video Transmitter In order for the UAV to transmit video from an onboard camera, a video transmitter is needed. The paparazzi AP sends all telemetry data down with the video on the audio channel portion of the transmitter. This means that the transmitter must have an audio channel. These vary in power, and thus range, and run normally on 2.4Ghz. Small UAVs can get about 600m of range from the 50mW version, and extended range can be achieved using units up to 1W. Weight for these units varies from a couple grams to about 30 for the 1W with shielding. Please check for your countries regulations on 2.4Ghz transmission, as each is different. Antennas Here are some examples of lightweight and efficient 868MHz antennas developped by the RF laboratory at ENAC. 868MHz copper foil antenna attached to the aircraft tail 868MHz copper foil antenna bottom view 868MHz ground antenna