novice
Posts: 90
Joined: Tue Aug 07, 2012 2:55 pm

Primary Radar

Wed Sep 19, 2012 12:03 am

Primary Radar;
Wavelength of 30-50cm
Pulse length 4 microseconds (us)
Horizontal beamwidth 1.7 degrees
Aerial rotation 5 RPM

Can anyone explain what the difference the between wavelength and pulse length of a primary radar?

Cheers
 
Fabo
Posts: 1151
Joined: Tue Aug 16, 2005 1:30 am

RE: Primary Radar

Wed Sep 19, 2012 12:27 am

wavelength is the distance where the wave pattern is repeating (eg. pattern is up, down, down back up to zero, and then again - like a sinusoide), as in, the distance that the signal will make in about the pulselength.

Pulse length is time in which one wave pattern is emmited from the antenna, and frequency is how manny patterns are emmited in one second. 4 microseconds is therefore about 250Hz if I calculate correctly.
The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
 
9VSIO
Posts: 654
Joined: Tue Dec 19, 2006 5:00 pm

RE: Primary Radar

Wed Sep 19, 2012 2:43 am

Pulse length is also known as period, right?
Me: (Lining up on final) I shall now select an aiming point. || Instructor: Well, I hope it's the runway...
 
HaveBlue
Posts: 2114
Joined: Fri Jan 30, 2004 3:01 pm

RE: Primary Radar

Wed Sep 19, 2012 3:54 am

Quoting 9VSIO (Reply 2):
Pulse length is also known as period, right?

If that's true, then I hate being around my girlfriend when she's on her 'pulse length'...  
Here Here for Severe Clear!
 
SAAFNAV
Posts: 391
Joined: Wed Mar 17, 2010 5:41 pm

RE: Primary Radar

Wed Sep 19, 2012 4:26 am

Quoting HaveBlue (Reply 3):

If that's true, then I hate being around my girlfriend when she's on her 'pulse length'...

OWM.... Nearly chocked on my coffee! Hate those damn Pulse Lenghts...  
L-382 Loadmaster; ex C-130B Navigator
 
David L
Posts: 8553
Joined: Tue May 18, 1999 2:26 am

RE: Primary Radar

Wed Sep 19, 2012 8:40 am

Radar doesn't transmit continuously, otherwise it would be difficult to tell which part of the signal is being reflected. Instead, it sends a short pulse, stops to listen for a return from that pulse then repeats. The pulse is a short transmission of a signal at a certain wavelength. The pulse length is the length of time each pulse is actively transmitted.

In the example in the OP, each pulse is a signal with a wavelength of 30-50cm which is transmitted for 4 microseconds at a time.

See the diagram here: http://meteorologytraining.tpub.com/14271/css/14271_58.htm

Quoting 9VSIO (Reply 2):
Pulse length is also known as period, right?

The period is the inverse of the frequency. Since frequency is measured in Hertz, or cycles per second, the period is seconds per cycle - i.e. how long it takes the wave to go from one peak to the next.
 
User avatar
Jetlagged
Posts: 2562
Joined: Sun Jan 23, 2005 3:00 pm

RE: Primary Radar

Wed Sep 19, 2012 6:34 pm

Quoting 9VSIO (Reply 2):
Pulse length is also known as period, right?

It's the wavelength which is also known as the period.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
novice
Posts: 90
Joined: Tue Aug 07, 2012 2:55 pm

RE: Primary Radar

Wed Sep 19, 2012 8:01 pm

Thanks for that explanation David L  
 
speedbird128
Posts: 1562
Joined: Tue Oct 28, 2003 2:30 am

RE: Primary Radar

Sun Sep 30, 2012 1:27 pm

Quoting David L (Reply 5):
it sends a short pulse, stops to listen for a return from that pulse then repeats

= PRF.
A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7

Who is online

Users browsing this forum: tealnz and 2 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos