Tips and Tricks

    1) Do NOT place your transmitter in a black nosecone.  Temperatures in excess of 100 degrees C have been measured inside dark colored  nosecones even when the  temperature outside is just 26C.  White is best!

    2) Do NOT place your transmitter inside a carbon fiber enclosure.  Carbon Fiber blocks both the transmitted RF signal and the incoming GPS signals. Plastic or fiberglass is best.

    3) Do NOT use metallic paint.  Problems similar to those related to carbon fiber can occur.

    4) Do NOT transmit more often than once every 5 seconds.  Frequent RF transmissions can affect quality of the GPS reception.

General Questions

Selection Guide:

Which BeeLine Transmitter should I choose?

There are two models of BeeLine Transmitter.  Both are simple beacons that transmit a callsign via morse code and emit a periodic FM or CW pulse.  The only difference between the two models is the power output.  The BeeLine MP emits approx 100mw, while the standard BeeLine emits approx 16mw.  The BeeLine MP will also consume the battery about 8x faster than the unamplified version using the same battery.

Which BeeLine GPS should I choose?

There are three different models of BeeLineGPS.  All of them transmit the current position (latitude, longitude and altitude) which is then decoded by a remote receiver.

70cm BeeLine GPS:

This model operates on the 420-450Mhz amateur radio band, and has a power output of approx 100milli-watts.  Range in the air is more than 40 miles.   Designed for high power rocketry,   it is powered by a single cell lithium poly battery (4.2V). It transmits data in industry standard APRS packets, a  "TNC" is required to decode the data packets.  See the radios section for more details.  Amateur radio license required.

This device contain a MAX-7 gps module from u-blox and can store 2 1/2 hours of latitude/longitude/altitude at 1 hz.

2M High Power BeeLine GPS

This model operates on the 144 Mhz amateur radio band, and has a power output of approx 6 watts.  Range in the air is more than 300 miles.  This unit was designed for tracking of high altitude balloons, automobiles, and general tracking purposes..  It can by powered by 4x AA battery, a dual cell lithium poly battery (8.4V), or 12V automotive power. It transmits data in industry standard APRS packets, a  "TNC" is required to decode the data packets.  See the radios section for more details.  Amateur radio license required..  This units can be configured with a SiRF III gps module or a Trimble Lassen IQ for high altitude applications.

900 Mhz BeeLine GPS

This model operates on a license free section of the 900 Mhz radio band, and has a power output of approx 250 milli-watts.  Range in the air is about 15 miles.  It is powered by a single cell lithium poly battery (4.2V). It transmits data in a propriety format.  BigRedBee supplies a matching receiver with optional LCD display.   This transmitter is FCC certified, and no license is required from the user.


Model 70cm BeeLine GPS (100mw) 2 Meter High Power BeeLine GPS 900 Mhz BeeLIne GPS
Frequency 420-450 Mhz (70cm amateur radio band) 140-150Mhz (2M amateur radio band) 900Mhz Spread Spectrum
Power output 100mw 6 watts 250mw
Range in the air > 70 miles > 300 miles approx 6 miles
Amateur License required? Yes Yes No
Receiver? Commercially available Commercially available available from BigRedBee
Data storage? Approx 8000 waypoints Approx 8000 waypoints Approx 8000 waypoints
Power source 3.5-9.0 V 4.0-9.0 V or 12-16V 3.5-9.0V
GPS Module u-blox MAX 7 u-blox MAX 7 u-blox MAX 7

Are there any concerns regarding the battery?

YES: Lithium poly batteries can be destroyed if overcharged or over discharged. Always use an appropriate charger. NEVER discharge below 3 volts. Even though the BeeLine Transmitters have a low voltage shutdown feature, the battery can still be over discharged. Always turn the transmitter off when not in use.

Why do I need an amateur (ham) radio license?

The radio spectrum used by the 2 meter and 70 cm  BigRedBee transmitters is regulated by the FCC in the United States. The FCC requires that you be a licensed amateur radio operator to transmit on these frequencies. These frequencies may or may not be regulated in other countries.  YOU are responsible for making you follow all applicable rules and regulations in your country.

The 900 Mhz transmitters do NOT require a license in the United States, Canada, or Australia. 

What frequency should I use?
As a licensed amateur radio operator, you are free to use any frequency in the 70cm band. Please consult the ARRL band plans for recommendations and restrictions. You may want to avoid repeater inputs/outputs and the weak signal areas, especially in populated areas.

Where should I put my BigRedBee?
The BigRedBee Transmitter should be treated like any other piece of sensitive electronics. The circuit board can withstand very high G flights, but is not potted. The best place to put your transmitter is in the nosecone or a payload bay. Simply wrap in bubble wrap and jam it in! Close proximity to altimeters and other electronics should be avoided due to concerns of RF from the transmitter adversely affecting other electronics. Attaching directly to the shock cord is not recommended, unless the transmitter is enclosed in some protective container.

What about composite airframes?
Carbon Fiber and metal will block RF signals. Phenolic, cardboard, fiberglass and other composites are OK.

How long does the battery last?
That depends on the transmitting parameters programmed into the BeeLine. With a 10% duty cycle (.5 seconds on, 4.5 seconds off) and 10 minutes between call sign transmissions, a new, fully charged battery will last for more than 48 hours.

Can I use my own battery?
Yes. Any battery providing at least 3.2V and not more than 9V can be used to power the transmitter. The supplied lithium poly battery has a fully charged voltage of 4.25V, and should not be discharged below 3.2V

Can I use my own battery charger?
Yes, but it must be specifically designed to charge single cell
lithium polymer batteries.

What's the range of this transmitter?
That depends on number of things such as quality of the receiver, gain of the antenna, and terrain. This transmitter has been tracked from 10 miles out using a handheld ham receiver, and 20 miles using a more sensitive mobile rig and larger car mounted antenna. The signal was clearly hear for the duration of the N2N flight to 40,000 feet. The most important variable is terrain. At 433 Mhz, RF waves don't 'follow' the ground well, and are easily blocked by small hills.

What kind of serial cable should I use?
The serial adapter is designed to plug directly into a standard DB-9 serial port. If you use a cable, make sure it is a straight through extension cable, and not a 'null modem' cable, or other kind of cable that swaps pins. Using the wrong cable will result in timeouts, and may damage the serial adapter.

Are kits available?
No. Only fully assembled boards are offered for sale.

Can the BeeLine transmit telemetry data?
No, you need a BeeLine GPS transmitter to transmit data packets.

How do I program my BeeLine Transmitter?
You need to download the BeeLine Communicator. The latest version is

My PC doesn't have hyperterminal, what should I use to monitor the serial data stream?
I recommend Tera Term , others have successfully used 'putty'.

What kind of antenna should I use?.
1) Build your own:
2) Buy one, I recommend this:
3) Or, for base operation, I have this one (not a directional yagi):

Does the programming software run under Linux?
No, but one customer has reported that it worked fine using a windows emulator, WINE version 0.9.17.

BeeLine Transmitter

How big is it?
The BeeLine Transmitter (B1) is .88" wide x 1.725" long.

The BeeLine MP Transmitter (B6)  is .79" wide x 1.9375" long.

Both weigh approx 6 grams without the antenna or battery.

BeeLine GPS

How big is it?

The 100mw (version A5)  u-blox 70cm BRB GPS is 1.230" wide x 2.825" long. 

The 850 mah battery weighs 25 grams and is approx 1.28" wide.

The original (Lassen IQ) 70cm BeeLine GPS is 1.225" wide x 2.865"  long and weighs 25 grams w/out the battery. 

The 2M High power GPS is 1.255" wide x 3.635" long and weighs 56 grams w/out battery or antenna

The 900 Mhz transmitter weighs 25 g without battery, and is 28mm wide x 67mm long