1. A method for requesting information regarding a network subscriber station in a network of distributed stations, where the network subscriber station has a reserved memory area for the station-specific information, wherein the requesting network subscriber station first uses a block read access operation to request the station-specific information from the network subscriber station which is to be requested, and, if this block read access operation is answered with an error code, the requesting network subscriber station rerequests the station-specific information using word read access operations.
2. The method as claimed in claim 1, wherein the request for the station-specific information is ended when a word read access operation is answered with an error code again.
3. The method as claimed in claim 1, wherein the error code taken into account which initiates the fresh request for the station-specific information is an address error code.
4. The method as claimed in claim 3, wherein the error code taken into account which initiates the fresh request for the station-specific information is also an access-type error code.
5. The method as claimed in claim 1, wherein the reserved memory area corresponds to the configuration ROM in an IEEE 1394 network subscriber station.
6. The method as claimed in claim 3, wherein the address error code corresponds to the error code \u201cresp_address_error\u201d or \u201cack_address_error\u201d.
7. The method as claimed in claim 4, wherein the access-type error code corresponds to the error code \u201cack_type_error\u201d or to the error code \u201cresp_type_error\u201d based on the IEEE 1394 standard.
8. The method as claimed in claim 1, wherein the station-specific information requested is contents of the IEEE 1394 configuration ROM.
9. The method as claimed in claim 1, wherein the word read access operation corresponds to a quadlet read access operation.
10. A network subscriber station for carrying out the method as claimed in claim 1, having means for requesting information from another network subscriber station using a block read access operation or a word read access operation, wherein the station-specific information from the other network subscriber station is requested by virtue of the requesting network subscriber station having been set up such that it first uses a block read access operation to request the station-specific information and, if this block read access operation is answered with an error code, such that it rerequests the station-specific information using word read access operations.
11. The network subscriber station as claimed in claim 10, wherein the error code which is taken into account and initiates the fresh request for the station-specific information is an address error code.
12. The network subscriber station as claimed in claim 11, wherein the further error code taken into account which initiates the fresh request for the station-specific information is also an access-type error code.
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 counting device comprising:
counting means for counting the number of signals input during a counting interval, the number of signals having a linear relationship with a physical quantity, and the signals having a substantially single frequency when the physical quantity is constant;
period measurement means for measuring a period of a signal every time a signal is input during the counting interval;
frequency distribution generating means for generating a frequency distribution of signal periods during the counting interval from a measurement result obtained by said period measurement means;
representative value calculation means for calculating a representative value of a distribution of periods of signals from the frequency distribution generated by said frequency distribution generating means; and
correction value calculation means for obtaining a total sum Ns of frequencies in a class not more than a first predetermined multiple of the representative value calculated by said representative value calculation means and a total sum Nw of frequencies in a class not less than a second predetermined multiple of the representative value from the frequency distribution generated by said frequency distribution generating means, and correcting a count result obtained by said counting means on the basis of the frequencies Ns and Nw.
2. A device according to claim 1, wherein said representative value calculation means calculates one of a median, a mode, and an average as a representative value.
3. A device according to claim 1, wherein said correction value calculation means obtains a count result N\u2032 after correction from a count result N by said counting means according to N\u2032=N+Nw\u2212Ns.
4. A device according to claim 1, wherein said correction value calculation means obtains the total sums Ns and Nw of frequencies in classes with the first predetermined multiple and the second predetermined multiple being 0.5 and 1.5, respectively.
5. A distance meter comprising:
a semiconductor laser which emits laser beam to a measurement target;
a laser driver which causes said semiconductor laser to operate such that a first oscillation interval including at least an interval in which an oscillation wavelength continuously and monotonically increases and a second oscillation interval including at least an interval in which the oscillation wavelength continuously and monotonically decreases are alternately present;
a signal acquisition device which acquires an electrical signal containing an interference waveform caused by laser beam emitted from said semiconductor laser and optical feedback from the measurement target;
counting means for counting the number of interference waveforms contained in an output signal from said signal acquisition device;
period measurement means for measuring a period of an interference waveform every time an interference waveform is input during the counting interval;
frequency distribution generating means for generating a frequency distribution of periods of interference waveforms during the counting interval from a measurement result obtained by said period measurement means;
representative value calculation means for calculating a representative value of a distribution of periods of interference waveforms from the frequency distribution generated by said frequency distribution generating means;
correction value calculation means for obtaining a total sum Ns of frequencies in a class not more than a first predetermined multiple of the representative value calculated by said representative value calculation means and a total sum Nw of frequencies in a class not less than a second predetermined multiple of the representative value from the frequency distribution generated by said frequency distribution generating means, and correcting a count result obtained by said counting means on the basis of the frequencies Ns and Nw; and
arithmetic means for obtaining a distance to the measurement target from a count result corrected by said correction value calculation means.
6. A meter according to claim 5, wherein said signal acquisition device is a light-receiving device which converts interference light between laser beam and optical feedback into an electrical signal.
7. A meter according to claim 5, wherein said signal acquisition device comprises a detector which detects an electrical signal containing an interference waveform caused by a self-mixing effect between laser beam and optical feedback.
8. A meter according to claim 7, wherein said detector comprises a light-receiving device which converts an optical output from said semiconductor laser into an electrical signal.
9. A meter according to claim 7, wherein said detector comprises a voltage detection circuit which detects a voltage between terminals of said semiconductor laser.
10. A meter according to claim 5, wherein said representative value calculation means calculates one of a median, a mode, and an average as a representative value.
11. A meter according to claim 5, wherein said correction value calculation means obtains a count result N\u2032 after correction from a count result N by said counting means according to N\u2032=N+Nw\u2212Ns.
12. A meter according to claim 5, wherein said correction value calculation means obtains the total sums Ns and Nw of frequencies in classes with the first predetermined multiple and the second predetermined multiple being 0.5 and 1.5, respectively.
13. A counting method comprising the steps of:
counting the number of signals input during a counting interval, the number of signals having a linear relationship with a physical quantity, and the signals having a substantially single frequency when the physical quantity is constant;
measuring a period of a signal every time a signal is input during the counting interval;
generating a frequency distribution of signal periods during the counting interval from a period measurement result;
calculating a representative value of a distribution of periods of signals from the frequency distribution; and
obtaining a total sum Ns of frequencies in a class not more than a first predetermined multiple of the representative value and a total sum Nw of frequencies in a class not less than a second predetermined multiple of the representative value from the frequency distribution, and correcting the number of signals counted on the basis of the frequencies Ns and Nw.
14. A method according to claim 13, wherein the step of calculating comprises the step of calculating one of a median, a mode, and an average as a representative value.
15. A method according to claim 13, wherein the step of correcting comprises the step of obtaining a count result N\u2032 after correction from a count N of signals according to N\u2032=N+Nw\u2212Ns.
16. A method according to claim 13, wherein the step of correcting comprises the step of obtaining the total sums Ns and Nw of frequencies in classes with the first predetermined multiple and the second predetermined multiple being 0.5 and 1.5, respectively.
17. A distance measuring method comprising the steps of:
causing a semiconductor laser to operate such that a first oscillation interval including at least an interval in which an oscillation wavelength continuously and monotonically increases and a second oscillation interval including at least an interval in which the oscillation wavelength continuously and monotonically decreases are alternately present;
acquiring an electrical signal containing an interference waveform caused by laser beam emitted from the semiconductor laser and optical feedback from a measurement target;
counting the number of interference waveforms contained in the acquired electrical signal;
measuring a period of an interference waveform every time an interference waveform is input during a counting interval in which the number of interference waveforms is counted;
generating a frequency distribution of periods of interference waveforms during the counting interval from a period measurement result;
calculating a representative value of a distribution of periods of interference waveforms from the frequency distribution;
obtaining a total sum Ns of frequencies in a class not more than a first predetermined multiple of the representative value and a total sum Nw of frequencies in a class not less than a second predetermined multiple of the representative value from the frequency distribution, and correcting the number of interference waveforms counted on the basis of the frequencies Ns and Nw; and
obtaining a distance to the measurement target from a corrected number of interference waveforms.
18. A method according to claim 17, wherein the step of acquiring comprises the step of converting interference light between laser beam and optical feedback into an electrical signal.
19. A method according to claim 17, wherein the step of acquiring comprises the step of detecting an electrical signal containing an interference waveform caused by a self-mixing effect between laser beam and optical feedback.
20. A method according to claim 19, wherein the step of detecting comprises the step of converting an optical output from the semiconductor laser into an electrical signal.
21. A method according to claim 19, wherein the step of detecting comprises the step of detecting a voltage between terminals of the semiconductor laser.
22. A method according to claim 17, wherein the step of calculating comprises the step of calculating one of a median, a mode, and an average as a representative value.
23. A method according to claim 17, wherein the step of correcting comprises the step of obtaining a count result N\u2032 after correction from a count result N of signals according to N\u2032=N+Nw\u2212Ns.
24. A method according to claim 17, wherein the step of correcting comprises the step of obtaining the total sums Ns and Nw of frequencies in classes with the first predetermined multiple and the second predetermined multiple being 0.5 and 1.5, respectively.