Garmin Astro GPS Dog Tracking Systems

Improving Signal Range for Garmin Astro 320 & 220 handheld receivers

Not many users of the Garmin Astro dog tracking system know that you can switch frequency to gain signal range. The Garmin Astro operates on five (5) different frequencies. These five frequencies are selectable in the handheld Garmin Astro 320 and 220 Receiver.

DC 20, DC 30 and DC 40 collar transmitters send a radio signal to your Garmin Astro 320 or 220 handheld receiver. The range of that radio signal depends on the terrain where you are tracking. If you are in a flat terrain like a field, you will experience the best results in signal range. But if you are tracking in a rough terrain with hills and valleys, you will experience a signal range that is reduced.

The signal range is also dependant on a few technical factors:

1. the output power of the transmitter on your DC 20, DC 30 or Garmin Astro DC 40 dog tracking collar.
2. the transmitter and receiver antennas
3. the frequency you have chosen on your handheld Garmin Astro 320 or 220 receiver

Output Power: The output power of Garmin Astro DC-20, DC 30 and DC 40 tracking collars is 2 Watts. This output power is a function of the product design and not changeable. When a radio transmitter operates on such a low output power, the main rule is to use the lowest radio frequency possible. The higher the frequency, the higher the output power it takes to deliver the signal.

NOTE: In some cases, depending on where you are hunting, the lowest frequency might not be the ultimate one. It is recommended that you to try all 5 frequencies to see which one is performing the best in your specific area of the world. When you try out the different frequencies, just be sure that you test each in the exact same area. Hang the Garmin Astro DC 40, DC 30 or DC-20 transmitter in a tree and take a ride with your car or bicycle. Please note that whenever you actually change the frequency, you must have the Garmin Astro 320 or 220 handheld receiver and the Garmin Astro DC-40, DC-30 or DC-20 very near each other.

Antennas: Choice of the antennas on the transmitters and receiver will have an effect on signal quality. Improved Garmin Astro DC 40 and DC 30 transmitters have a longer, higher performance, transmission antenna than the DC 20. If you have a DC-20 we carry a higher performance antenna that can be mounted on a harness. Some users have also experienced improved signal range when using the Garmin Magnetic Mount Antenna with their Astro 320 or 220 handheld instead of the original stock antenna.

Frequency: With the US version of the Garmin Astro, there are five (5) MURS* radio frequencies to work with:

151,82Mhz (ID code: 0-9)
151,88Mhz (ID code: 10-19)
151,94Mhz (ID code: 20-29)
154,57Mhz (ID code: 30-39)
154,60Mhz (ID code: 40-49)

The Scandinavian version of the Garmin Astro has only one frequency available: 155,42Mhz, transmitting on 2 Watts of output power.

*MURS stands for Multi-Use Radio Service and consists of these five frequencies in the VHF spectrum. As defined by the FCC, it is a private, two-way, short distance voice or data communications service for personal or business activities of the general public. In 2000, these frequencies were moved to become part of the new Citizens Band Radio Service (CB) which has been renamed MURS.

How to Switch Frequencies

Switching frequency on Astro 320 and 220 receivers is very easy and it is not published in the Garmin Astro User Manual. To change it, you simply need to change the pre-programmed ID code that your Garmin Astro DC-30 or DC-20 is using. For example, if your receiver is currently set to ID code: 43, you can see on the frequency table above that the radio frequency you are using is 154,60Mhz. In this example, for better signal range, you should try an ID code between 0 and 9 (e.g. 5) so the receiver is set on the lowest frequency: 151,82Mhz.

How to assign a new ID code to your receiver:

1. With the "Dog Tracker" page open and the Garmin Astro DC 40, DC-30 or DC-20 transmitter powered on, press MENU.
2. Select Change Comm. Settings.
3. Follow the on-screen instructions.
4. Select the desired ID-code and press OK
5. Choose the update rate you desire.
6. Follow the on-screen instructions to finish the setup.

This article was co-authored by America's Pet Store and may not be reproduced without permission. It has been written to provide general information on product selection and training. It is not intended to be a substitution for the information that comes with your product.