Variable frequency rate receiver
First Claim
1. A variable rate receiver for receiving phase shift key (PSK) data signals as an input data stream and producing drift free real time in-phase data signals at the output comprising:
- a tracking loop of the type including a voltage controlled oscillator coupled to said input data stream for producing a signal at the frequency of the carrier,a data detection loop coupled to said input data stream for producing real time data output signals,a comparator coupled to said data detection loop for detecting data transactions,electronic switch means coupled between said comparator and said tracking loop,phase lock detection means coupled to said electronic switch means and to said tracking loop and to said data detection loop for detecting when the voltage error signals in said tracking loop and in said data detection loop have reached a predetermined voltage difference indicating that the tracking loop is locked on to the phase and frequency of the carrier of the input data stream, andsaid phase lock detection means having means for closing said electronic switch means.
1 Assignment
0 Petitions
Accused Products
Abstract
A variable data rate receiver is provided which employs a novel phase locked loop (PLL) of the type employing a data detection loop and a tracking loop. The data detection loop is initially not coupled to the input of the voltage controlled oscillator in the tracking loop of the PLL, but is separated by an electronic switch. A phase lock detection circuit is provided which is coupled to the data detection loop and to the tracking loop for detecting the difference in the voltage error signals in the data detection loop and the tracking loop. When this error signal indicates that the tracking loop is locked on to the carrier signal the electronic switch is closed completing the phase locked loop circuit after lock on of the carrier is achieved.
-
Citations
17 Claims
-
1. A variable rate receiver for receiving phase shift key (PSK) data signals as an input data stream and producing drift free real time in-phase data signals at the output comprising:
-
a tracking loop of the type including a voltage controlled oscillator coupled to said input data stream for producing a signal at the frequency of the carrier, a data detection loop coupled to said input data stream for producing real time data output signals, a comparator coupled to said data detection loop for detecting data transactions, electronic switch means coupled between said comparator and said tracking loop, phase lock detection means coupled to said electronic switch means and to said tracking loop and to said data detection loop for detecting when the voltage error signals in said tracking loop and in said data detection loop have reached a predetermined voltage difference indicating that the tracking loop is locked on to the phase and frequency of the carrier of the input data stream, and said phase lock detection means having means for closing said electronic switch means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A method of decreasing the acquisition time in a variable data rate receiver which employs a phase lock loop circuit having a data detection loop and a tracking loop, comprising the steps of:
-
isolating said data detection loop from said tracking loop at the input to the tracking loop, providing an electronic switch at the input of said tracking loop, detecting the difference between the error voltage signal in said data detection loop and said tracking loop, closing said electronic switch between said data detection loop and said tracking loop to reconnect as an operable circuit the phase lock loop when the error voltage signal difference indicates that the tracking loop is locked on to the carrier signal. - View Dependent Claims (17)
-
Specification