Digital radio communications system with high noise immunity
First Claim
1. A radio transmitting system using a noise minimizing code, for selective calling of radio systems, using a selected multibit sequential binary word having a selected number of binary bits, such as 24, for example;
- and register means for storing said 24 bits;
comprising(a) means for coding said word of 24 sequential binary bits into a coded transmission of clocked trains of binary signal pulses, where each binary signal pulse of said binary signal comprises a square pulse of selected magnitude, polarity and duration D, followed by a space of equal duration D; and
wherein(b) for each bit of said 24 binary bits which is a logical one, first means to produce a train of a selected number M of said binary signal pulses; and
for each bit of said 24 binary bits which is a logical zero, second means to produce a train of a selected number N of binary signal pulses;
where N is substantially different from M;
(c) between the end of a first train of said binary pulses and the beginning of the next train, means for providing a clocked time space of zero signal equal in length to the length of P binary signal pulses, where P is less than M or N; and
(d) means to modulate a radio transmitter with said coded transmission.
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Abstract
A digital data radio transmission system, such as may be used in communicating point-to-point by radio, in which a keyboard is used to insert a multi-decimal-digit number representing the called station. This is fed to a decimal-to-binary converter, forming a train of binary bits which are then coded in a selected manner so as to be substantially noise immune. The output of the coder then goes to the radio transmitter. At the receiving end, a similar means is provided for obtaining and storing in a 24-bit register the selected number of the called station. The output of the radio detector is then decoded to obtain the 24-bit word representing the called station, which is stored in a second register. A comparator compares the numbers stored in the two registers. When they compare positively, an alarm signal is enabled, or the receiver squelch is broken.
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Citations
9 Claims
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1. A radio transmitting system using a noise minimizing code, for selective calling of radio systems, using a selected multibit sequential binary word having a selected number of binary bits, such as 24, for example;
- and register means for storing said 24 bits;
comprising(a) means for coding said word of 24 sequential binary bits into a coded transmission of clocked trains of binary signal pulses, where each binary signal pulse of said binary signal comprises a square pulse of selected magnitude, polarity and duration D, followed by a space of equal duration D; and
wherein(b) for each bit of said 24 binary bits which is a logical one, first means to produce a train of a selected number M of said binary signal pulses; and
for each bit of said 24 binary bits which is a logical zero, second means to produce a train of a selected number N of binary signal pulses;
where N is substantially different from M;(c) between the end of a first train of said binary pulses and the beginning of the next train, means for providing a clocked time space of zero signal equal in length to the length of P binary signal pulses, where P is less than M or N; and (d) means to modulate a radio transmitter with said coded transmission. - View Dependent Claims (2, 3, 4, 8, 9)
- and register means for storing said 24 bits;
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5. A radio receiving system using a noise minimizing code for selective calling of radio stations, in which the coded transmission comprises a series of 24 binary bits, for example, converted to clocked digital signal pulses in which each digital signal pulse comprises a square positive half-cycle of selected time duration D and a following space of equal time duration D, comprising;
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(a) a 24-bit first register for storing the binary word corresponding to the selected radio receiving station; (b) means to receive the coded transmission calling said selected receiving station; (c) means to decode said coded transmission to form a 24-bit received binary word, and a second 24-bit register means to store said 24-bit received binary word; (d) means to compare said 24-bit words in said first and second registers; and (e) means responsive to said means to compare to enable a ringing signal when said comparison is positive and in which said means to decode said coded transmission of digital signal pulses, comprises; (f) first means to count the number of digital signal pulses in a train; and
second means to determine the end of a train of digital pulses; and
counter means responsive to said first and second means;(g) third means responsive to said counter means to determine if a sufficient number of digital signals have been received to comprise a valid signal; (h) fourth means responsive to said counter means to determine whether the number of digital signal pulses in a train correspond to a binary one bit or a binary zero bit; and (i) fifth means responsive to said third and fourth means to clock into said second 24 bit register said determined binary bit.
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6. In a radio communication system for calling a selected radio receiver using a binary word indicative of the address of a selected receiver said binary word composed of a selected number B of sequential binary bits, which may be ones or zeros;
improved apparatus for coding said binary bits for noise immune transmission by radio, comprising; (a) means for providing a series of clocked trains of digital pulses, wherein each digital pulse comprises a square pulse of logic level one and of time duration D, followed by a space of logical level zero and of time duration D; (b) for each bit of said binary word which is a logical one, means to produce a train of a selected number M of digital pulses; and
for each bit of said binary word which is a logical zero, means to produce a train of a selected number N of digital pulses, where N can be greater than, or less than M, in a ratio of the order of approximately 2 to 1;(c) between the end of a first train of said digital pulses, and the beginning of the next train, means for providing an interbit space of zero signal level, comprising a clocked space equal to 2PD units of time, where P is a selected integer less than the smaller of M or N; and (d) means to modulate a radio transmitter in accordance with said series of trains of digital signal pulses. - View Dependent Claims (7)
Specification