Path: ...!eternal-september.org!feeder2.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Don Y Newsgroups: sci.electronics.design Subject: Re: IR detector system, biasing of photo diode Date: Tue, 29 Oct 2024 05:02:33 -0700 Organization: A noiseless patient Spider Lines: 26 Message-ID: References: <1r26sh6.eprne8sro2qcN%liz@poppyrecords.invalid.invalid> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Tue, 29 Oct 2024 13:02:38 +0100 (CET) Injection-Info: dont-email.me; posting-host="8f7ceb60878d932608b6ce95e8e41b6d"; logging-data="1631900"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19LG/aWXWEZDDzFSKSKuOL1" User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Cancel-Lock: sha1:2EXjZQtr2JjPjgVjRuE6iLWLINs= Content-Language: en-US In-Reply-To: <1r26sh6.eprne8sro2qcN%liz@poppyrecords.invalid.invalid> Bytes: 2384 On 10/29/2024 4:20 AM, Liz Tuddenham wrote: > Klaus Vestergaard Kragelund wrote: > > [...] >> >> If the chirp arrives at the same time at each mike, the robot is on the >> right path, If one is delayed, the robot eases into the that direction > > If one of the chirps has been reflected from a distant hard surface the > long delay could interfere with the next pulse. Something like that > happened to an early-warning radar sytem when the moon rose and > reflected long-delayed pulses. > > A slow pulse rate or a variable one would overcome this. ISTR Polaroid's ultrasonic ranging kit; the transducer was driven with pulses in a fixed pattern at four distinct frequencies. This helped the receiver determine the "envelope" for a single burst. In LORAN, the carrier was modulated with a specific envelope (as well as a pulse code pattern) to let the receiver identify a specific reference point on the carrier. (because multiple signal sources could be present in a given geographical area)