Low-tech solution provides hi-tech surveillance performance
When it comes to undercover police surveillance, holding a microphone up to your mouth can blow your cover. Try an inexpensive and easy-to-manufacture “hands-free” device for Motorola Spectra and most other mobile radios.
In today’s hi-tech world, it is becoming harder for police agencies to perform surveillance activities. Unless money is spent to add encryption protocol modules to all radios, most communications can be intercepted by one means or another. The average criminal, however, probably does not go to great lengths to keep tabs on the opposition. The first defense in keeping a surveillance activity covert is to ensure that the bad guys don’t even realize that your team members are using a radio.
If surveillance activities are kept discreet, and radios are kept out of sight, then in most cases the bad guys will think the “coast is clear.”
Most manufacturers of portable radios (as well as aftermarket companies) offer surveillance microphones and earphones for portables. That’s great if the area of operation is tight-like a shopping mall-where 5W, portable coverage is sufficient. The real-world challenge is when the operation requires driving all over town, getting on the interstate and following someone for 20 miles. This type of surveillance requires the higher transmit power of a mobile radio to cover potentially greater distances between team members.
Blown cover Using the hand-held mic of the mobile radio, however, becomes a problem. If the radio operator has to bring the mic up to the face to speak into it, the bad guys may realize that there is surveillance. If the mic is instead held down in the lap, the other team members have to set their speaker volumes to the highest level to hear. Any other person that uses a mic in the normal manner on that channel will “blast” the others out.
Hiding the evidence Although plenty of surveillance mic systems are available for portables, the same is not true for mobile radios. The following is a rather low-tech means of providing the function of pseudo “hands-free” transmit audio. It is easy to manufacture as well as to install. This package, shown in the photo at the left, can provide nearly the same level of modulation as holding the hand-held mic to the mouth. Because the “hands-free” mic is sensitive, it could also be used inside the undercover car to monitor and to remotely record a “transaction” unbeknownst to the bad guy (as long as the time-out timer of the mobile radio is turned off). A bonus safety feature is that when driving, the operator does not have to fumble for the mic and try to hold it up to his/her mouth while simultaneously trying to steer and negotiate traffic.
The hands-free mic can be clipped onto the sun visor in front of the driver/radio operator. The PTT/plunger switch cabling can be routed to a convenient location, such as on the seat, through the seatbelt eyelet. The mic cable is simply plugged into the mic jack of the control head.
The more recent versions of the Motorola Spectra remote-mount radio offer a mic jack on the front as well as on the back of the control head. Another option is to make the wiring connections at the DB-15 accessories connector on the back of the Spectra transceiver.
Customizations This “homemade package” uses a plunger-style PTT switch to allow easy installation and quick transfer among police officers or vehicles, as needs change. A permanent installation could use a discretely mounted PTT switch installed in the vehicle.
Although this setup was originally designed for use with a Spectra radio, the easy integration into most radios makes it a worthwhile investment. The connection directions in the box above include suggestions for alternate systems and parts.
