Capacitive batch counting to support one-way time-of-flight or other operations
A method includes receiving electromagnetic signals containing pulses. The method also includes converting the pulses contained in the electromagnetic signals into an electrical signal that identifies at least some of leading or trailing edges of the pulses. The method further includes repeatedly (i) accumulating the electrical signal to generate a voltage using an integrating circuit and (ii) resetting the integrating circuit in response to the voltage of the integrating circuit meeting or exceeding a threshold voltage. In addition, the method includes providing a count value identifying a number of times that the voltage of the integrating circuit meets or exceeds the threshold voltage. Each time the voltage of the integrating circuit meets or exceeds the threshold voltage is representative of a specific number of pulses received in the electromagnetic signals.
1. A method comprising:
receiving electromagnetic signals containing pulses;
converting the pulses contained in the electromagnetic signals into an electrical signal that identifies at least some of leading or trailing edges of the pulses;
repeatedly (i) accumulating the electrical signal to generate a voltage using an integrating circuit and (ii) resetting the integrating circuit in response to the voltage of the integrating circuit meeting or exceeding a threshold voltage; and
providing a count value identifying a number of times that the voltage of the integrating circuit meets or exceeds the threshold voltage;
wherein each time the voltage of the integrating circuit meets or exceeds the threshold voltage is representative of a specific number of pulses received in the electromagnetic signals.
2. The method of claim 1 , further comprising:
generating a digital output based on the voltage of the integrating circuit, the digital output indicating whether the voltage of the integrating circuit meets or exceeds the threshold voltage;
wherein the count value is based on the digital output.
3. The method of claim 1 , wherein converting the pulses contained in the electromagnetic signals into the electrical signal comprises;
identifying envelopes of the pulses contained in the electromagnetic signals;
comparing the envelopes to a reference voltage in order to generate an initial digital output having high and low values; and
detecting the leading or trailing edges of the pulses using the initial digital output.
4. The method of claim 3 , wherein:
detecting the leading or trailing edges of the pulses using the initial digital output comprises generating an output having positive and negative spikes that identify the leading and trailing edges of the pulses; and
converting the pulses contained in the electromagnetic signals into the electrical signal further comprises blocking the positive or negative spikes.
5. The method of claim 1 , wherein:
the electromagnetic signals comprise first electromagnetic signals;
the pulses comprise first pulses;
the electrical signal comprises a first electrical signal,
the method further comprises:
receiving second electromagnetic signals containing second pulses; and
converting the second pulses contained in the second electromagnetic signals into a second electrical signal that identifies at least some of leading or trailing edges of the second pulses; and
the integration circuit is repeatedly used to accumulate at least one of the first and second electrical signals.
6. The method of claim 1 , wherein:
the electromagnetic signals comprise incoming electromagnetic signals;
the method further comprises transmitting outgoing electromagnetic signals;
the outgoing electromagnetic signals contain pulses at first and second RF frequencies;
the incoming electromagnetic signals contain pulses at third and fourth RF frequencies; and
the outgoing and incoming electromagnetic signals are interleaved such that a pulse at the first RF frequency is transmitted, a pulse at the third RF frequency is received, a pulse at the second RF frequency is transmitted, and a pulse at the fourth RF frequency is received in a repeating pattern.
7. The method of claim 1 , wherein:
the pulses contained in the electromagnetic signals have varying amplitudes; and
converting the pulses contained in the electromagnetic signals into the electrical signal comprises generating pulses having a known amplitude in the electrical signal.
8. An apparatus comprising:
a front-end configured to convert pulses contained in received electromagnetic signals into an electrical signal that identifies at least some of leading or trailing edges of the pulses;
an integrating circuit configured to repeatedly (i) accumulate the electrical signal to generate a voltage and (ii) be reset in response to the voltage of the integrating circuit meeting or exceeding a threshold voltage; and
a counter configured to generate a count value identifying a number of times that the voltage of the integrating circuit meets or exceeds the threshold voltage;
wherein each time the voltage of the integrating circuit meets or exceeds the threshold voltage is representative of a specific number of pulses received in the electromagnetic signals.
9. The apparatus of claim 8 , further comprising:
a comparator configured to generate a digital output based on the voltage of the integrating circuit, the digital output indicating whether the voltage of the integrating circuit meets or exceeds the threshold voltage;
wherein the count value is based on the digital output.
10. The apparatus of claim 8 , wherein the front-end comprises:
an envelope detector configured to identify envelopes of the pulses contained in the electromagnetic signals;
a comparator configured to compare the envelopes to a reference voltage in order to generate an initial digital output having high and low values; and
an edge detector configured to identify the leading or trailing edges of the pulses using the initial digital output.
11. The apparatus of claim 10 , wherein:
the edge detector is configured to generate an output having positive and negative spikes that identify the leading and trailing edges of the pulses; and
the front-end further comprises a rectifier configured to block the positive or negative spikes.
12. The apparatus of claim 8 , wherein:
the electrical signal comprises a first electrical signal;
the apparatus further comprises a second front-end configured to convert second pulses contained in second received electromagnetic signals into a second electrical signal that identifies at least some of leading or trailing edges of the second pulses; and
the integration circuit is configured to repeatedly accumulate at least one of the first and second electrical signals.
13. The apparatus of claim 8 , wherein:
the electromagnetic signals comprise incoming electromagnetic signals;
the apparatus further comprises at least one signal source configured to generate outgoing electromagnetic signals, the outgoing electromagnetic signals containing pulses at first and second RF frequencies;
the incoming electromagnetic signals contain pulses at third and fourth RF frequencies; and
the apparatus is configured to use a repeating pattern in which the outgoing and incoming electromagnetic signals are interleaved such that a pulse at the first RF frequency is transmitted, a pulse at the third RF frequency is received, a pulse at the second RF frequency is transmitted, and a pulse at the fourth RF frequency is received.
14. The apparatus of claim 8 , wherein:
the pulses contained in the electromagnetic signals have varying amplitudes; and
the front-end is configured to generate pulses having a known amplitude in the electrical signal.
15. An apparatus comprising:
a first node configured to transmit first electromagnetic signals to a second node and receive second electromagnetic signals from the second node;
wherein the first node comprises:
a front-end configured to convert pulses contained in the second electromagnetic signals into an electrical signal that identifies at least some of leading or trailing edges of the pulses;
an integrating circuit configured to repeatedly (i) accumulate the electrical signal to generate a voltage and (ii) be reset in response to the voltage of the integrating circuit meeting or exceeding a threshold voltage; and
a counter configured to generate a count value identifying a number of times that the voltage of the integrating circuit meets or exceeds the threshold voltage, wherein each time the voltage of the integrating circuit meets or exceeds the threshold voltage is representative of a specific number of pulses received in the electromagnetic signals.
16. The apparatus of claim 15 , wherein:
the first node further comprises a comparator configured to generate a digital output based on the voltage of the integrating circuit, the digital output indicating whether the voltage of the integrating circuit meets or exceeds the threshold voltage; and
the count value is based on the digital output.
17. The apparatus of claim 15 , wherein the first node further comprises at least one processing device configured to identify, based on the count value generated as a result of repeated transmissions and receptions of the first and second electromagnetic signals, a time-of-flight associated with a travel time for one of the electromagnetic signals to travel between the first and second nodes, the time-of-flight indicative of a distance between the nodes.
18. The apparatus of claim 15 , wherein the front-end comprises:
an envelope detector configured to identify envelopes of the pulses contained in the second electromagnetic signals;
a comparator configured to compare the envelopes to a reference voltage in order to generate an initial digital output having high and low values; and
an edge detector configured to identify the leading or trailing edges of the pulses using the initial digital output.
19. The apparatus of claim 15 , wherein:
the second electromagnetic signals contain pulses at different RF frequencies;
the front-end is configured to receive the second electromagnetic signals at one of the RF frequencies;
the first node further comprises a second front-end configured to convert second pulses contained in the second electromagnetic signals at another of the RF frequencies into a second electrical signal; and
the integration circuit is configured to repeatedly accumulate at least one of the first and second electrical signals.
20. The apparatus of claim 15 , wherein:
the first electromagnetic signals contain pulses at first and second RF frequencies;
the second electromagnetic signals contain pulses at third and fourth RF frequencies; and
the first node is configured to use a repeating pattern in which the first and second electromagnetic signals are interleaved such that a pulse at the first RF frequency is transmitted, a pulse at the third RF frequency is received, a pulse at the second RF frequency is transmitted, and a pulse at the fourth RF frequency is received.