他们的仪器探测到了频率为3千赫的非常微弱的无线电波。

Their instruments detected very faint radio waves at a frequency of 3 kilohertz.

该过滤器都是连续可调，并从20赫兹到20千赫两个频带范围。

The filters are both continuously adjustable , with a range from 20 Hz to 20 kHz in two bands.

输出频率可在中心频率(56.448兆赫)附近连续微调。调整范围为65千赫。

Its output frequency can be adjusted continuously around the center frequency (56.448 MHz) over a range of 65 KHz.

直接阻抗测量100千赫至500兆赫，可以用任择41951a阻抗检测试剂盒。

Direct impedance measurements from 100 kHz to 500 MHz can be performed using the optional 41951a impedance test kit.

或许最有趣的频率这里是518千赫，被使用为海安全和航海信息传输通过FSK 。

Perhaps the most interesting frequency here is 518 kHz, used for transmission of maritime safety and navigation information via FSK.