2019年、福島・おおたかどや山のJJY(40kHz)の記念ベリカードを貰うために、今は通販休止中のラジオ少年で購入した35mmφ×200mmの極太フェライト・コアでバーアンテナを作り、HFアップバータ付きのRTL SDRドングルで受信して当初の目的を果たしました。 それ以降 ...

With such wide beam angle, it's may be hard to see a good echo. You can check the bestarttech 200kHz transducer (beam angle 7deg) we have used here Please check this posting also (if you have not ...

If you can sacrifice quite a bit of resolution then it may certainly be good to use something like a 40kHz transducer. But if you need some resolution then perhaps using something like 100kHz or ...

Method: a transmitter and transducer are taped together (separation distance 0). An oscilloscope (Keysight DSO-X 3014A) waveform generator is set to 5V peak-to-peak sine wave, and the receiver is ...