Radio frequency distance determination

A radio frequency transceiver device arranged to:

• receive a radio frequency signal from a target;
• determine a time domain channel response from the radio frequency signal;
• determine an amplitude of a largest peak in the time domain channel response;
• determine an amplitude of a second, earlier, peak in the time domain channel response;
• compare the second peak amplitude to a threshold based on the largest peak amplitude;
• identify the largest peak as a shortest path peak if the second peak amplitude is less than the threshold;
• identify the second peak as a shortest path peak if the second peak amplitude is greater than the threshold;
• identify a closest local minimum in the time domain channel response earlier than the shortest path peak;
• determine a time separation between the closest local minimum and the shortest path peak;
• compare the time separation to an expected time separation based on a bandwidth of the received radio frequency signal;
• calculate the distance between the radio frequency device and the target based on a time corresponding to the shortest path peak;
• and
• if the time separation is greater than the expected time separation, calculate said time corresponding to the shortest path peak as a time corresponding to the closest local minimum plus the expected time separation.

A method of determining a distance between a radio frequency device and a target, the method comprising:

• the radio frequency device transmitting a first radio frequency signal;
• the radio frequency device receiving a second radio frequency signal from the target based on the first radio frequency signal;
• determining a time domain channel response from the second radio frequency signal;
• determining an amplitude of a largest peak in the time domain channel response;
• determining an amplitude of a second, earlier, peak in the time domain channel response;
• comparing the second peak amplitude to a threshold based on the largest peak amplitude;
• identifying the largest peak as a shortest path peak if the second peak amplitude is less than the threshold;
• identifying the second peak as a shortest path peak if the second peak amplitude is greater than the threshold;
• identifying a closest local minimum in the time domain channel response earlier than the shortest path peak;
• determining a time separation between the closest local minimum and the shortest path peak;
• comparing the time separation to an expected time separation based on a bandwidth of the received radio frequency signal;
• calculating the distance between the radio frequency device and the target based on a time corresponding to the shortest path peak;
• and
• if the time separation is greater than the expected time separation, calculating said time corresponding to the shortest path peak as a time corresponding to the closest local minimum plus the expected time separation.

A radio frequency transceiver device arranged to:

• transmit a first radio signal;
• receive a second radio frequency signal from a target based on the first radio frequency signal;
• determine a time domain channel response from the second radio frequency signal;
• determine an amplitude of a largest peak in the time domain channel response;
• determine an amplitude of a second, earlier, peak in the time domain channel response;
• compare the second peak amplitude to a threshold based on the largest peak amplitude;
• identify the largest peak as a shortest path peak if the second peak amplitude is less than the threshold;
• identify the second peak as a shortest path peak if the second peak amplitude is greater than the threshold;
• identify a closest local minimum in the time domain channel response earlier than the shortest path peak;
• determine a time separation between the closest local minimum and the shortest path peak;
• compare the time separation to an expected time separation based on a bandwidth of the received radio frequency signal;
• calculate the distance between the radio frequency device and the target based on a time corresponding to the shortest path peak;
• and
• if the time separation is greater than the expected time separation, calculate said time corresponding to the shortest path peak as a time corresponding to the closest local minimum plus the expected time separation.