FM Transmission

The typical drive-in broadcasts the film soundtrack over low-power FM, but these transmitters were designed for re-broadcasting around the home or hobbyist and don't offer the sound quality that today's discerning movie-goer expects.

We supply class leading professional quality Eddystone Broadcast XE10 FM transmitter systems that can easily be adjusted from practically nothing, all the way to 10 watts from the front panel, this means we can turn the power up and down, enabling us to achieve exactly the right coverage for each site.

They broadcast through tuned ¼-wave ground plane antennas mounted to masts on the roofs of the projection buildings. Output of the transmitters is adjusted for a clean signal on the drive-in fields.

The digital sound systems work as follows: The sound is output from the projector often as a 5.1 LPCM bitstream or analogue to our professional digital mixer to allow for level control, EQ, compassion and automation that is essential for good quality sound. The signal then feeds the transmitter and antenna.

This results in sound that is equal in quality to the local FM commercial stations. Our transmitters have built-in audio processing minimising FM hum or background noise, and the frequency response is good out to around 15kHz. This represents a quantum leap over the sound is experienced with older more traditional transmitters.

As part of our trusted package we supply Deva SmartGen RDS encoders that will identify your Drive-In Cinema by name on the car radio's display and continuously transmit any promotional or sponsors advertising message to your audience.

FM Transmission
General Range Up to 700m (depending on licence and site)
Number of cars No technical limit
Audio Quality Equivalent to FM Local Radio Station - Medium Quality
Requires OFCOM site specific licence being granted to promoter Illegal to use without
Pros Fixed cost irrespective of number of patrons
Quick to install
Cons Variable sound quality dependant on patron's car audio
No guarantee all car radio receivers will be able to tune in
Modern vehicles may prohibit car radio ON without engine / ignition running
Modern vehicles can demand car "side lights" ON with radio
Vehicles can experience flat engine start batteries at end of performance
No control over "car next door" excessive volume level
Promotor has no control over successful audio delivery
Unsuitable for live mixing
Display TMC and EWS Services
RDS/RBDS complient
Identify transmission by format
Cinema name on the car radio's display
Continuously transmit promotional message
WEB Interface programming
Technical Frequency Range 87.5 to 108MHz in 50kHz steps
Frequency Stability < ± 200Hz
Power output 1W to 10W adjustable
Harmonic and spurious output < -75dBc (9kHz to 1GHz)
Spurious outputs < -85dBc (87.5MHz to 137MHz @ greater than 500kHz removed from carrier)
Synchronous Noise 0.3% @ ± 40kHz deviation (excluding pilot) at a modulation frequency of 400Hz
Input sensitivity + 8dBu (adjustable) for ± 67.5kHz deviation: 5.5V peak to peak
MPX Response < ± 0.2dB (5Hz - 15kHz)
AF THD (multiplex version) Power Supply (AC) < 0.1% @ ± 67.5kHz deviation over 40Hz to 10kHz
Power Supply (AC) 88-264VAC, 47-63Hz