72 MHz or 216 MHz for Assisted Listening Devices
72 – 75 MHz vs. 216 MHz
Each frequency band has different advantages over the other. Consider the following questions to help determine the right frequency for your particular application:
- Do I have a very long range that needs to be covered?
- Is distance of transmission a top priority?
- Is there a need to use more than (3) three frequencies simultaneously?
- Is audio quality a main concern?
- If using an external antenna, what is the clearance space with the ceiling?
- Is the transmission going to be used primarily outdoors?
- What length of cable will be used from the transmitter to the antenna?
- Which frequency is less likely to have interference with other signals?
Answering these questions will give you a better idea of which frequency will best suit your application. Here are a few facts and details about the two frequencies:
The transmission range doubles when using the 216 MHz frequency band. Using a dipole antenna (more efficient) the 72 MHz frequency has a transmission range of 1,500 ft. (457 m). With the same scenario 216 MHz will broadcast up to 3,000 ft. (914 m) line of site. In portable applications, using the LT-700 Portable Display FM Transmitter, the range is the same with both frequencies – 150 ft (45.7 m).
Because the 72 MHz band is larger, up to (6) six channels can be used simultaneously, while only (3) three channels can be used concurrently with the 216 MHz band.
Good info I needed today while working on an AV specification.