Frequency-hopped single sideband mobile radio system
First Claim
1. In a system for communicating a message signal (s(t))a transmitter (10) responsive to said message signal for producing as an output a carrier-frequency-hopped single sideband signal (s'"'"'hop (t)), wherein said transmitter comprisescarrier-frequency-hopping generating means (16) for generating as an output a unique sequence of separate carrier frequencies (fi (t)) from a plurality of N possible carrier frequencies (F1,F2, . . . ,FN);
- multiplying means (12, 14,
18) responsive to both said message signal and said unique sequence of carrier frequencies for multiplying said message signal with said unique sequence of carrier frequencies and producing as an output of said transmitter the carrier-frequency-hopped single sideband signal; and
a receiver (20) responsive to said carrier-frequency-hopped single sideband signal produced by said transmitter and receiving therefrom said message signal, wherein said receiver comprisescarrier-frequency-hopping generating means (24) for generating as an output said unique sequence of separate carrier frequencies generated by said transmitter carrier-frequency-hopping generating means, said receiver carrier-frequency-hopping generating means also capable of producing as an output an assignment code (c(t)) associated with said unique sequence of carrier frequencies wherein said transmitter carrier-frequency-hopping generating means is responsive to said assignment code generated by said receiver carrier-frequency-hopping generating means for producing as an output said unique sequence of carrier frequencies related thereto; and
demodulating means (22, 26,
28) responsive to both the received carrier-frequency-hopped single sideband signal (s'"'"'hop (t)) and said unique sequence of separate carrier frequencies for demodulating said received carrier-frequency-hopped single sideband signal in accordance with said unique sequence of separate carrier frequencies and producing as an output of said receiver the message signal applied as an input of said transmitter.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention relates to a frequency-hopped single sideband (SSB) mobile radio system implemented by hopping the carrier frequency of an input signal (s(t)) every τ seconds. The hopping is controlled by a carrier-frequency-hopped sequence (fi (t)) generated by a carrier-frequency-hopping generator (16,24). When employed in a frequency-hopped SSB transmitter (10), the carrier sequence functions to modulate the input signal, "hopping" it to a different carrier frequency every τ seconds. The carrier-frequency-hopped SSB receiver (20) employs the identical carrier sequence as used by the transmitter to demodulate the transmitted carrier-frequency-hopped SSB signal, thereby recovering the original single sideband signal (s(t)). By frequency hopping the carrier signal of an SSB signal, the present invention mitigates the effects of co-channel interference and frequency selective fading inherent in prior art SSB cellular mobile radio systems.
-
Citations
11 Claims
-
1. In a system for communicating a message signal (s(t))
a transmitter (10) responsive to said message signal for producing as an output a carrier-frequency-hopped single sideband signal (s'"'"'hop (t)), wherein said transmitter comprises carrier-frequency-hopping generating means (16) for generating as an output a unique sequence of separate carrier frequencies (fi (t)) from a plurality of N possible carrier frequencies (F1,F2, . . . ,FN); -
multiplying means (12, 14,
18) responsive to both said message signal and said unique sequence of carrier frequencies for multiplying said message signal with said unique sequence of carrier frequencies and producing as an output of said transmitter the carrier-frequency-hopped single sideband signal; anda receiver (20) responsive to said carrier-frequency-hopped single sideband signal produced by said transmitter and receiving therefrom said message signal, wherein said receiver comprises carrier-frequency-hopping generating means (24) for generating as an output said unique sequence of separate carrier frequencies generated by said transmitter carrier-frequency-hopping generating means, said receiver carrier-frequency-hopping generating means also capable of producing as an output an assignment code (c(t)) associated with said unique sequence of carrier frequencies wherein said transmitter carrier-frequency-hopping generating means is responsive to said assignment code generated by said receiver carrier-frequency-hopping generating means for producing as an output said unique sequence of carrier frequencies related thereto; and demodulating means (22, 26,
28) responsive to both the received carrier-frequency-hopped single sideband signal (s'"'"'hop (t)) and said unique sequence of separate carrier frequencies for demodulating said received carrier-frequency-hopped single sideband signal in accordance with said unique sequence of separate carrier frequencies and producing as an output of said receiver the message signal applied as an input of said transmitter. - View Dependent Claims (2, 3)
-
-
4. A transmitter (10) for communicating a message signal (s(t)) wherein said transmitter is responsive to said message signal for producing as an output a carrier-frequency-hopped single sideband signal s'"'"'hop (t)), wherein said transmitter comprises
carrier-frequency-hopping generating means (16) for generating as an output a unique sequence of separate carrier frequencies (fi (t)) from a plurality of N possible carrier frequencies; - and
multiplying means (12, 14,
18) responsive to both said message signal and said unique sequence of separate carrier frequencies for multiplying said message signal with said unique sequence of carrier frequencies and producing as an output of said transmitter the carrier-frequency-hopped single sideband signal, where the multiplying means comprisesa first bandpass filter (12) responsive to the message signal for producing as an output a filtered message signal r(t) equal to the portion of said message signal appearing in a predetermined frequency range (fa -fb); a multiplier (14) responsive to both said filtered message signal and the unique sequence of separate carrier frequencies for producing as an output a carrier-frequency-hopped message signal (Shop (t)) equal to the multiplicative produce thereof; and a second bandpass filter (18) responsive to both said carrier-frequency-hopped message signal and said unique sequence of separate carrier frequencies for removing unwanted components from said carrier-frequency-hopped message signal and producing as an output of said transmitter the carrier-frequency-hopped single sideband signal (s'"'"'hop (t)).
- and
-
5. A receiver (20) capable of receiving and demodulating a carrier-frequency-hopped single sideband signal (s'"'"'hop (t)) and recovering therefrom a message signal (s(t)) wherein the receiver comprises
carrier-frequency-hopping generating means (24) for generating as an output a unique sequence of separate carrier frequencies relates to the received carrier-frequency-hopped single sideband signal; - and
demodulating means (22, 26,
28) responsive to both said received carrier-frequency-hopped single sideband signal and said unique sequence of separate carrier frequencies for demodulating said received carrier-frequency-hopped single sideband signal in accordance with said unique sequence of separate carrier frequencies and producing as an output of said receiver the message signal related thereto, wherein the demodulating means comprisesa first bandpass filter (22) responsive to both the received carrier-frequency-hopped single sideband signal and the unique sequence of carrier frequencies for producing as an output a filtered carrier-frequency-hopped single sideband signal (r(t)); a multiplier (26) responsive to both said filtered carrier-frequency-hopped single sideband signal and said unique sequence of carrier frequencies for producing as an output a multiplicative product thereof (d(t)); and a second bandpass filter (28) responsive to said multiplicative product signal for removing unwanted components therefrom and producing as an output of said receiver the message signal related thereto.
- and
-
6. A communication system employing single sideband modulation, comprising
a plurality of M mobile units, each mobile unit capable of accepting a separate message signal (s1 (t)-sm (t)), multiplying means in each mobile unit for multiplying a separate message signal by a separate one of a plurality of M distinct carrier-frequency-hopping sequences (f1 (t)-fm (t)) to produce as an output a separate one of a plurality of M unique carrier-frequency-hopped single sideband signals (s'"'"'hop,1 (t)-s'"'"'hop,M (t)); - and
a base station responsive to and capable of demodulating said plurality of M unique carrier-frequency-hopped single sideband signals and recovering therefrom a plurality of M separate message signals (s1 (t)-sm (t)). - View Dependent Claims (7, 8, 9)
- and
-
10. A communication system employing single sideband modulation, comprising
a plurality of mobile units, each mobile unit capable of accepting a separate message signal, multiplying means in each mobile unit for multiplying separate message signal by a separate one of a plurality of distinct carrier-frequency-hopping sequences and said plurality of mobile units is capable of producing as an output a plurality of unique carrier-frequency-hopped single sideband signals; - and
a plurality of base stations, each base station encompassing a distinct geographic area and contiguous base stations alloted a separate portion (B1 -B7) of a predetermined total frequency band wherein each base station comprises a carrier-frequency-hopping generating means for generating a plurality of distinct carrier-hopping frequencies such that each carrier element of each sequence of said plurality of distinct sequences resides in said alloted portion of said total frequency band such that each base station is capable of communicating with any mobile units located in its associated geographic area. - View Dependent Claims (11)
- and
Specification