Emergency vehicle radio transmission system

An apparatus for transmitting a selected signal from a first vehicle to a second vehicle comprising:

• a. a frequency selection element for selecting a plurality of frequencies which are active at a particular location;
• b. a modulation element for modulating the selected signal and for providing a modulated signal therefrom;
• c. a frequency control element coupled to said frequency selection element and further coupled to said modulation element for stepping a reference frequency signal through a plurality of pre-mix frequencies at a predetermined rate, each of said plurality of pre-mix frequencies corresponding to one of said plurality of selected frequencies;
• d. a mixing element coupled to said modulation element and further coupled to said frequency control element for mixing said modulated signal and said reference frequency signal, and for providing a post-mix signal therefrom;
• and
• e. a transmitting element coupled to said mixing element for transmitting said post-mix signal from said first vehicle to said second vehicle.

A method for providing a local signal from a first vehicle having a location to a second vehicle wherein a number of remote transmitters are collectively transmitting a number of remote signals on a number of selected frequencies at the location of the first vehicle, the method comprising the steps of:

• a. determining the selected frequencies of the remote signals at the location of the first vehicle, said determining step providing a plurality of preselected frequencies;
• b. sending said local signal over a first one of said plurality of preselected frequencies to said second vehicle;
• c. sending said local signal over a next one of said plurality of preselected frequencies to said second vehicle;
• d. ascertaining if said local signal has been sent over all of said plurality of preselected frequencies;
• and
• e. repeating step (c) if said ascertaining step concludes that said local signal has not been sent over all of said plurality of preselected frequencies.

A method for providing a local signal from a first vehicle having a location to a second vehicle wherein a number of remote transmitters are collectively transmitting a number of remote signals on a number of selected frequencies at the location of the first vehicle, the method comprising the steps of:

• a. determining the selected frequencies of the remote signals at the location of the first vehicle, said determining step providing a plurality of preselected frequencies;
• b. sampling said local signal at a predetermined rate thereby providing a sampled signal;
• and
• c. time division multiplexing said sampled signal over all of said plurality of preselected frequencies.

A method for providing a local signal from a first vehicle having a location to a second vehicle, comprising:

• a. determining the frequencies of a number of remotely generated signals that are active at the location of the first vehicle, said determining step (a) providing a plurality of preselected frequencies;
• b. modulating said local signal thereby providing a modulated signal;
• c. mixing said modulated signal with a reference frequency signal thereby providing a post-mix signal having a frequency, said reference frequency signal having a corresponding frequency associated therewith, said frequency of said reference frequency being such that the frequency of said post-mix signal corresponds to one of said plurality of preselected frequencies;
• d. providing a next reference frequency signal having a next corresponding frequency associated therewith, said next frequency of said next reference frequency signal being such that the resulting post-mix signal corresponds to the next one of said plurality of preselected frequencies;
• and
• e. repeating steps (c) and (d).

A method for providing a signal over a number of frequencies, wherein the signal has a corresponding Nyquist sample rate, the method comprising the steps of:

• a. sampling the signal at or above the Nyquist sample rate of the signal, wherein the sampling step samples the signal during a number of sample periods;
• a. providing the signal over a first one of the number of frequencies during a first one of the number of sample periods;
• and
• c. providing the signal over a second one of the number of frequencies during a second one of the number of sample periods.