Talk:Doppler radar

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doppler radar[edit]

the policeman's picture is out of place as most 'speed guns' actually use a multiplicity of range readings vs. pulse time — Preceding unsigned comment added by (talk) 13:42, 25 April 2017 (UTC)

Merge Pulse-Doppler radar Here[edit]

While pulse Doppler radar works on phase shift an CW/FM work Doppler effect, both type of radars are called Doppler. Therefore it would be best to merge both article into this one and explain completely the concepts. Pierre cb 14:04, 4 November 2006 (UTC)

That might be a major undertaking, as each subject hasn't changed much in a year due to the daunting task of putting it all in eighth-grade English. 17:50, 5 December 2006 (UTC)

It is important that there is a distinction made between weather radar and "normal" radar. When searching for radar information Wikipedia doesn't make that distinction, yet while they work on the same principles they are distinctly different

There is a Weather radar article that is independant of the two articles to merge and explain the use of pulse-pair to extract velocity data. Pulse-Doppler radar and Doppler radar articles are not about weather but just the principle of using radar to record the velocities of targets two different ways (the first one used by weather radars). Using the name of Doppler radar for weather radar is an American misnomer as this type of weather radar was introduce by the National Weather Service and the confusion popularized by television stations. Wikipedia should stop this confusion. Pierre cb 18:33, 6 December 2006 (UTC)

I don't believe that merging this Topic with Pulse-Doppler radar is helpful. Although both use the Doppler principle, the two systems are totally different. The most common use of PD Radar is in attack radars for military aircraft, and these systems utilise a number of other phenomena in order to work, such as coherency, pulse profiling etc (I can't comment on its use in weather radar, because I have no experience of these systems). Doppler radar techniques are most often found in ground speed computational systems, such as might be found as part of a navigation system, or as a hover aid in helicopters. The applications are sufficiently diverse to warrant two entries, although the linkage between them is relevant. User:TJC

Since there seems to be no dissent, I'll remove the merge proposal sometime during the weekend.--Terry C 13:26, 12 January 2007 (UTC)

Not detected at all?[edit]

If non-moving objects can not be detected by Doppler radars then how come the weather radars detect ground echoes? Assuming I'm right, the following needs re-writing:

"A target with no range-rate reflects a frequency near the transmitter frequency, and cannot be detected. The classic zero doppler target is one which is on a heading that is tangential to the radar antenna beam. Basically, any target that is heading 90 degrees in relation to the antenna beam cannot be detected." --Weedrat (talk) 11:23, 20 April 2008 (UTC)

First, modern weather radars are Pulse-Doppler radars so this Doppler radar is not the right article (see weather radar article). Second, Dopplerized weather radar detect ground echoes, as any echoes, with their conventional reflectivities and then post treatment looks for zero velocities for those echoes to flag them as ground echoes. As mentionned in the quoted text, echoes moving perpendicular to the line of sight of the radar will have a zero velocity, that does not means they will not be detected by they reflectivities. It just means that they cannot be detected by velocities. Pierre cb (talk) 03:46, 17 July 2008 (UTC)

Radial velocity[edit]

In your openind paragraph you mention that doppler measures "radial velocity' In theory doppler cannot measure radial veleocity as it needs to detect a relativement movement towards or away from the radar. If a target moves radially at a constant distance there is no doppler effect per se - known a "blind Speed' Brat87

Sorry but radial velocity is EXACTLY a movement toward or away from the radar, along a radial axis to the radar. An object cannot move radially and stay at the same distance from a radar. What you are thinking of is a tangantial movement which has a zero radial velocity as the radar beam is perpendicular to the motion. At any other angle there will be a radial component compared to the scanning radar and a thus a radial velocity which is only a component of the real velocity. Pierre cb (talk) 23:39, 3 April 2009 (UTC)

"The doppler processor can only process velocities up to ±1/2 the PRF of the radar" makes little sense.[edit]

PRF is a frequency, not a velocity. Does the author mean that the numeric value of the PRF pulses, say 150 in one second, must be divided by 2 (75) to get the upper limit of detectable speed? The succeeding sentence limiting detection velocity to <75 mph due to low PRF sample rates does make sense. Please fix the bad sentence or remove it. Douglas Nelson Turner (talk) 15:19, 15 October 2014 (UTC)