In this article, we are going to learn about the blind speed definition, what blind speed is in radar and how can the blind speed problem in radar be solved. So let’s start with the definition of Blind speed.

**Blind Speed**

Blind Speed is a very serious problem in MTI Radar. When the Doppler shift equals an integer multiple of PRF (Pulse Repetition Frequency), the delay line canceller not only eliminate the DC components caused by the clutter but it also rejects moving targets.

In other words, blind speed can be explained as the relative velocities at which the MTI response is zero called **Blind Speed**.

The response from the single delay line canceller will be zero, when

\boxed{f_d=n/T=nf_r}

Where, n = 0, 1, 2, 3, ….; T = PRT, and f_{r} is the PRF.

The n^{th} blind speed V_{n} can be expressed as

\boxed{V_n= \frac{n \lambda}{2T} = \frac{n\lambda f_r}{2}}

Where, n = 1, 2, 3, …

if \lambda is in meters, fr is in hz, and the relative velocity is in knots.

The blind speed is written as

\boxed{v_n=\frac{n\lambda f_r}{1.02} \approx n\lambda f_r}

**How can the Blind Speed problem in radar be solved**

The limitations of blind speed can be reduced up to some extent by employing the following steps:

- Operate the radar at long wavelength (means low frequency)
- Operate with a higher PRF.
- Operate with more than one PRF
- operate with more than one RF frequency.