PowerFLARM Portable - Firmware Update Available - Mode C Traffic Now Supported

Dave, Unless your sqawking 7700 then by all means ident away And if you
don't know what 7700 means you shouldnt own a transponder

CH
(PS its not hard to **** off ATC at all!)

At 14:42 19 January 2012, Steve Leonard wrote:
On Jan 18, 6:40=A0pm, Dave Nadler wrote:

No, pressing IDENT does NOT cause the transponder to transmit.
It merely sets an attention flag for controllers
(which highlights you on their display).
If the controllers did not request an IDENT,
they will not be amused.

Please do not do that...

Thanks,
Best Regards, Dave "YO electric"

Hmm. Then I wonder what my transponder and PCAS equipped friends were
doing then to locate each other on a cross country flight? Radio
transmissions were as follows.

"Where are you?"
"I will give you an update. There."
"Oh, you are 240 degrees from me, 9.8 miles."

Later.

"I did get that update. Give it again. Got it. You are now 270
degrees, 5.5 miles."

Maybe I mis-understood what was going on? Maybe they were just "not
amusing" local ATC? If pressing IDENT sets an attention flag on the
ground radar display, it had to transmit something.

Haven't done it. Won't do it. Suggestion for others to do it
withdrawn.

Steve
Not an expert.
Never claimed to be.
Just smart enough to be dangerous.

I would like to understand this point about IDENT better.

As I understand it, a transponder TRANSmits when it is interrogated by
ATC SSR or when stimulated by TCAS, when it becomes a resPONDER to
that stimulus. Hence its name.

If IDENT is pressed when within reach of ATC, I can see how that would
flag it on their screen.

If not within reach of ATC SSR, does it transmit anyway, not in
response to anything?

Chris N.
(No agenda, just asking.)

Don't know the answer for sure, but the reply indicator on my Trig turns on
when I press the IDENT button. I think I'll send them an email and see what
they say.


"Chris Nicholas" wrote in message
...
I would like to understand this point about IDENT better.

As I understand it, a transponder TRANSmits when it is interrogated by
ATC SSR or when stimulated by TCAS, when it becomes a resPONDER to
that stimulus. Hence its name.

If IDENT is pressed when within reach of ATC, I can see how that would
flag it on their screen.

If not within reach of ATC SSR, does it transmit anyway, not in
response to anything?

Chris N.
(No agenda, just asking.)

On 1/19/2012 6:42 AM, Steve Leonard wrote:

Hmm. Then I wonder what my transponder and PCAS equipped friends were
doing then to locate each other on a cross country flight? Radio
transmissions were as follows.

"Where are you?"
"I will give you an update. There."
"Oh, you are 240 degrees from me, 9.8 miles."

Later.

"I did get that update. Give it again. Got it. You are now 270
degrees, 5.5 miles."

Maybe I mis-understood what was going on? Maybe they were just "not
amusing" local ATC? If pressing IDENT sets an attention flag on the
ground radar display, it had to transmit something.

Haven't done it. Won't do it. Suggestion for others to do it
withdrawn.

What PCAS were they using that gave them direction?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

On Jan 19, 7:14*pm, Eric Greenwell wrote:

What PCAS were they using that gave them direction?


--
Eric Greenwell - Washington State, USA

Turns out I was wrong about what they had on board. They each had a
Garmin Rino, two way radio, GPS, tracker, etc.

Please continue to ignore my lack of knowledgeon some of these devices
that I have not been using. :-)

Steve

On 19/01/2012 11:40, Dave Nadler wrote:
On Wednesday, January 18, 2012 6:37:04 PM UTC-5, Andy wrote:
That seems to imply that you think pressing IDENT will cause the
transponder to transmit, or am I mistaken?

No, pressing IDENT does NOT cause the transponder to transmit.
It merely sets an attention flag for controllers
(which highlights you on their display).
If the controllers did not request an IDENT,
they will not be amused.

I'd be interested to know how pressing IDENT causes a flag to be set on
the controller's display 100 miles away without any transmission from
the transponder. Telepathy?

GC


Please do not do that...

Thanks,
Best Regards, Dave "YO electric"

On Jan 20, 3:15*am, GC wrote:

I'd be interested to know how pressing IDENT causes a flag to be set on
the controller's display 100 miles away without any transmission from
the transponder. *Telepathy?

GC

As my education continues to rise, allow me to pass along what I think
I have learned. When you press the IDENT button, you tell your
transponder "If I get interrogated in the next X seconds, reply with
this extra bit of information as well." And X seconds is the amount
of time your "reply" light is on after you push the IDENT button.
This additional information that is sent will be received by the
ground station and set a flag to highlight you on the display for the
controller.

Have not personally verified this, but have gotten the same info from
what I consider to be a couple of VERY good sources. So, it is not
done via telepathy, but anticipation. You are asked to IDENT, you do,
and you prepare your transponder for the next interrogation.

See how much we learned this week? :-)

Having installed a Trig TT22 in my LAK-17a, I've noted that, when I press
the IDENT button, the reply indicator turns on for some finite time which is
longer than a normal reply to an interrogation. Since I know absolutely
nothing about transponder protocol, I sent a message to Trig's tech support
and got a very detailed reply about how it works.

Not wanting to step on any toes (unusual for me, huh?), I replied to Andy at
Trig thanking him for the information and requesting permission to post his
reply. If he says, "Yes", I'll post it here.

In the mean time, Steve's info sounds correct to me.


"Steve Leonard" wrote in message
...
On Jan 20, 3:15 am, GC wrote:

I'd be interested to know how pressing IDENT causes a flag to be set on
the controller's display 100 miles away without any transmission from
the transponder. Telepathy?

GC

As my education continues to rise, allow me to pass along what I think
I have learned. When you press the IDENT button, you tell your
transponder "If I get interrogated in the next X seconds, reply with
this extra bit of information as well." And X seconds is the amount
of time your "reply" light is on after you push the IDENT button.
This additional information that is sent will be received by the
ground station and set a flag to highlight you on the display for the
controller.

Have not personally verified this, but have gotten the same info from
what I consider to be a couple of VERY good sources. So, it is not
done via telepathy, but anticipation. You are asked to IDENT, you do,
and you prepare your transponder for the next interrogation.

See how much we learned this week? :-)

On Jan 20, 7:43*am, "Dan Marotta" wrote:
Having installed a Trig TT22 in my LAK-17a, I've noted that, when I press
the IDENT button, the reply indicator turns on for some finite time which is
longer than a normal reply to an interrogation. *Since I know absolutely
nothing about transponder protocol, I sent a message to Trig's tech support
and got a very detailed reply about how it works.

Not wanting to step on any toes (unusual for me, huh?), I replied to Andy at
Trig thanking him for the information and requesting permission to post his
reply. *If he says, "Yes", I'll post it here.

In the mean time, Steve's info sounds correct to me.

"Steve Leonard" wrote in message

...
On Jan 20, 3:15 am, GC wrote:



I'd be interested to know how pressing IDENT causes a flag to be set on
the controller's display 100 miles away without any transmission from
the transponder. Telepathy?

GC

As my education continues to rise, allow me to pass along what I think
I have learned. *When you press the IDENT button, you tell your
transponder "If I get interrogated in the next X seconds, reply with
this extra bit of information as well." *And X seconds is the amount
of time your "reply" light is on after you push the IDENT button.
This additional information that is sent will be received by the
ground station and set a flag to highlight you on the display for the
controller.

Have not personally verified this, but have gotten the same info from
what I consider to be a couple of VERY good sources. *So, it is not
done via telepathy, but anticipation. *You are asked to IDENT, you do,
and you prepare your transponder for the next interrogation.

See how much we learned this week? *:-)

From my Becker 4401-3 manual.
Pressing Ident button (will)............. In mode A and Mode A+C this
triggers the transmission of an identification impulse additional to
the Mode A reply code for approx 18 seconds. During this time "idt"
appears in the bottom line of the LC display.
It says, "triggers the tranmission"
I'm just say'n,
JJ

On Jan 20, 8:42*am, JJ Sinclair wrote:
On Jan 20, 7:43*am, "Dan Marotta" wrote:









Having installed a Trig TT22 in my LAK-17a, I've noted that, when I press
the IDENT button, the reply indicator turns on for some finite time which is
longer than a normal reply to an interrogation. *Since I know absolutely
nothing about transponder protocol, I sent a message to Trig's tech support
and got a very detailed reply about how it works.

Not wanting to step on any toes (unusual for me, huh?), I replied to Andy at
Trig thanking him for the information and requesting permission to post his
reply. *If he says, "Yes", I'll post it here.

In the mean time, Steve's info sounds correct to me.

"Steve Leonard" wrote in message

....
On Jan 20, 3:15 am, GC wrote:

I'd be interested to know how pressing IDENT causes a flag to be set on
the controller's display 100 miles away without any transmission from
the transponder. Telepathy?

GC

As my education continues to rise, allow me to pass along what I think
I have learned. *When you press the IDENT button, you tell your
transponder "If I get interrogated in the next X seconds, reply with
this extra bit of information as well." *And X seconds is the amount
of time your "reply" light is on after you push the IDENT button.
This additional information that is sent will be received by the
ground station and set a flag to highlight you on the display for the
controller.

Have not personally verified this, but have gotten the same info from
what I consider to be a couple of VERY good sources. *So, it is not
done via telepathy, but anticipation. *You are asked to IDENT, you do,
and you prepare your transponder for the next interrogation.

See how much we learned this week? *:-)

From my Becker 4401-3 manual.
Pressing Ident button (will)............. In mode A and Mode A+C this
triggers the transmission of an identification impulse additional to
the Mode A reply code for approx 18 seconds. During this time "idt"
appears in the bottom line of the LC display.
It says, "triggers the tranmission"
I'm just say'n,
JJ

JJ and Dan,

My vague understanding of how SSR (Secondary Surveillance Radar) works
will probably help make sense of the Ident function. The classic SSR
setups use a highly directional transmit/receive antenna that rotates
at either 6 or 15 RPM (if I remember correctly). The transmitter
emits inquiry pulses as it rotates, when a reply is received, the
rotational position is used to determine azimuth, the delay between
the last transmission and the reply determines distance. Pushing
Ident simply sets a flag within the transponder that results in a
specific bit being set (in addition to the selected code) in the reply
when the next inquiry is received. The flag remains set for 18
seconds to ensure that at least one Ident reply is transmitted. Note,
though, that if the antenna isn't pointing at you, it can't see the
reply, so (at least for Mode C transponders) when you press Ident,
nothing is transmitted unless an SSR inquiry is received within the
next 18 seconds...

Marc