US005241961A
United States Patent [19] [u] Patent Number: 5,241,961
Henry [45] Date of Patent: Sep. 7,1993
OTHER PUBLICATIONS
Harris et al, "Medical Instrumentation", vol. 21, No. 6 Dec. 1987, pp. 304-312.
Marko, "Aerospace Medicine", vol. 32, Nov. 1961 pp. 1019-1022.
Briskman, "Electronics", Sep. 6, 1963, pp. 31-37. Kennedy, G. "Electronic Communication Systems," 2d ed., 575-581 (1977).
Schwartz, M. "Information Transmission, Modulation,
and Noise," 2d ed., 176-183 (1970).
Crenner, F. "Simple Decoder for PPM Multichannel
Biotelemetry," Medical and Biological Engineering and
Computing 26(1):105-109.
Lovely, D. F. et al., "Micropower Pulse-position Modulator for Time-shared Applications," 24(5):531-535 (Sep. 1986).
Wen, H. Ko et al., "Single Frequency RF Powered
ECG Telemetry System," 26(2):105-109 (Feb. 1979).
Primary Examiner—William E. Kamm
Attorney, Agent, or Firm—Woodard, Emhardt,
Naughton, Moriarty & McNett
[57] ABSTRACT
A synchronous telemetry receiver and receiving method for reception from an implantable medical device of a PPM signal including a plurality of bits each having a sync pulse and at least one data pulse of equal amplitude. Capability is provided for restoring correct phase in the event that a sync pulse is missing or incorrectly received for any reason. A high-frequency clock and counter are provided for counting clock pulses during the time interval between each data pulse and its respective sync pulse in order to obtain a measurement of the time interval.
9 Claims, 10 Drawing Sheets
FV-^DATA
-2-J !,,4 STRING
tT^-SYNC
Vpulse
