1. Method for generating a digital video signal from an analog input video signal comprising:
detecting the type of signal source;
in case the type of signal source is a non-standard type, detecting the existence of an operating state where errors are likely to occur;
converting the analog input video signal to a digital video signal;
in case an operating state where errors are likely to occur exists, replacing an error prone part of the digitized video signal with a substitute signal part; and
in case the type of signal source is a standard type or no operating state where errors are likely to occur exists, keeping the digitized video signal unchanged.
2. Method according to claim 1, wherein the non-standard type of signal source is an apparatus for playback or recording of a tape.
3. Method according to claim 1, wherein the operating state where errors are likely to occur is a trick mode of the signal source.
4. Method according to claim 1, wherein the analog input video signal is a CVBS signal.
5. Method according to claim 1, wherein the digitized video signal is an ITU656 signal.
6. Method according to claim 5, wherein the error prone part of the digitized video signal is the field bit of a header.
7. Method according to claim 6, wherein an internal signal of a video converter having a stable timing is used for replacing the field bit.
8. Method according to claim 7, wherein for replacing the field bit the whole field is shifted by a determined number of lines.
9. Method according to claim 8, wherein the determined number of lines is adjustable.
10. Apparatus for receiving andor recording a digital video signal, having an input for receiving an analog video signal and means for digitizing a received analog video signal, wherein the apparatus performs the method according to claim 1 for generating a digital video signal from the received analog video signal.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system for receiving data from an implantable medical device, comprising:
an antenna for receiving a signal transmitted from the implantable device;
circuitry for computing a spectrum of the received signal;
circuitry for detecting a noise spectrum of the received signal by subtracting a template spectrum from the spectrum of the received signal, the template spectrum representing a noise-free signal;
circuitry for scaling the template spectrum such that the signal power of the noise spectrum is minimized;
circuitry for identifying frequency peaks in the noise spectrum in accordance with spectral thresholds derived from the signal power of the noise spectrum;
one or more notch filters for removing noise from the received signal, the notch filters having notch frequencies corresponding to frequency peaks of the detected noise spectrum;
a filter generator for updating filter coefficients of the notch filters so that the notch frequencies correspond to the detected noise spectrum.
2. The system of claim 1 wherein the filter generator is configured to set the notch frequencies of the notch filters to match those spectral components of the noise spectrum that exceed a specified spectral threshold value.
3. The system of claim 2 wherein the specified spectral threshold value is calculated as a specified number of standard deviations from the mean of the noise spectrum.
4. The system of claim 1 wherein the filter coefficients of the notch filters are periodically updated by the filter generator.
5. The system of claim 4 wherein the filter coefficients of the notch filters are updated based upon samples of the received signal that are continuously input into a buffer.
6. The system of claim 1 wherein the notch filters are digital infinite impulse response filters synthesized with notch frequencies corresponding to the detected noise spectrum.
7. The system of claim 1 wherein the circuitry for computing a spectrum of the received signal is configured to do so by sampling the received signal and discrete Fourier transforming the samples to produce a power spectrum of the received signal.
8. The system of claim 7 wherein the spectrum of the received signal is produced by summing the power spectra of a series of transformed sample sets of the received signal.
9. The system of claim 1 wherein the circuitry for identifying frequency peaks in the noise spectrum derives spectral thresholds in accordance with the mean and standard deviation of the noise spectrum.
10. The system of claim 9 wherein the circuitry for detecting the noise spectrum is configured to compute the noise spectrum as:
Pn=Pi\u2212R*Pe
where Pi is the power spectrum of the received signal, Pe is the template spectrum corresponding to the noise-free signal, and R is a scaling factor chosen to minimize Pn.
11. A method for receiving data from an implantable medical device, comprising:
receiving a signal transmitted from the implantable device;
computing a spectrum of the received signal;
detecting a noise spectrum of the received signal by subtracting a template spectrum from the spectrum of the received signal, the template spectrum representing a noise-free signal;
scaling the template spectrum such that the signal power of the noise spectrum is minimized;
identifying frequency peaks in the noise spectrum in accordance with spectral thresholds derived from the signal power of the noise spectrum;
removing noise from the received signal with one or more notch filters, the notch filters having notch frequencies corresponding to frequency peaks of the detected noise spectrum;
updating filter coefficients of the notch filters so that the notch frequencies correspond to the detected noise spectrum.
12. The method of claim 11 further comprising setting the notch frequencies of the notch filters to match those spectral components of the noise spectrum that exceed a specified spectral threshold value.
13. The method of claim 12 wherein the specified spectral threshold value is calculated as a specified number of standard deviations from the mean of the noise spectrum.
14. The method of claim 11 further comprising periodically updating the filter coefficients of the notch filters.
15. The method of claim 14 further comprising periodically updating the filter coefficients of the notch filters based upon samples of the received signal that are continuously input into a buffer.
16. The method of claim 11 wherein the notch filters are digital infinite impulse response filters synthesized with notch frequencies corresponding to the detected noise spectrum.
17. The method of claim 11 further comprising sampling the received signal and discrete Fourier transforming the samples to produce a power spectrum of the received signal.
18. The method of claim 17 further comprising summing the power spectra of a series of transformed sample sets of the received signal.
19. The method of claim 11 further comprising identifying frequency peaks in the noise spectrum by deriving spectral thresholds in accordance with the mean and standard deviation of the noise spectrum.
20. The method of claim 19 further comprising computing the noise spectrum as:
Pn=Pi\u2212R*Pe
where Pi is the power spectrum of the received signal, Pe is the template spectrum corresponding to the noise-free signal, and R is a scaling factor chosen to minimize Pn.