Beamscanner
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Posts posted by Beamscanner
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should be .8 sec hold for SPOT
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The ALR-45 should have PRF (sometimes called 'raw') audio fed from the crystal video receivers... I hope HB use wav/ogg files instead of their hex code approach in the viggen RWR. That way I could share some of the awesome radar audio I've made.
Loop play for best effect:
SA-6 target acquisition radar:
SA-6 target tracking radar:
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Thanks for the info guys. I look forward to proper MSI implementation.
1 hour ago, Jak525 said:You could also select SIL on the Attack format. The HAFU remains there, since the FLIR (in Autotrack) contributes to MSI. Although no range or altitude data.
A few other methods exist too; e.g. designate a Radar trackfile as the L&S, go to FLIR L+S slave, then command Autotrack from the FLIR format. Alternatively you can TDC depress over empty space on the Az/El FLIR format, slew over a track, and then release which commands the FLIR to be slaved to that trackfile's LOS. From there you could go to the FLIR format and Autotrack. Then once ultimately in Autotrack you can SILence the Radar or go into full EMCON mode to shut off other radio emitters.
I feel like the latter two methods should work now actually...
Yea, the silent button is dropping both tracks. Not just the radar track.
very interested in the FLIR cueing via the Az/El page though
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What is your approach to EMCON engagements?
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I tried to transition a radar only lock to a FLIR only lock, but I cant change SOI during ACM/STT and thus cant transition to a FLIR lock.
It would make sense if the FLIR attempted to autolock when slaved in ACM/STT, since you cant change SOI without dropping the lock.
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If I get a combined lock while in TWS, selecting silent or EMCON drops both locks, not just the radar lock.
The only way I've been able to have a FLIR only lock is to silence the radar first, and then manually slew the FLIR onto a target.
Is there something I'm missing? I dont think the FLIR should be dropping locks upon selection of EMCON or SIL.
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Also, shouldn't there be a FLIR button in the Az/El page?
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6 hours ago, Harlikwin said:
I was hoping you'd show up.
so question... The other part where it seems like you'd get some bang for your buck is the sensitivity of the receiver. Is it known how much of a difference you could expect from say something built with different generations of components i.e. GaS components vs GaN or so forth? Or put another way how much more sensitive would something built in the 80's or 90's be vs the 2000's.
Similar question on signal proc, like how much more does having 80's vs 90s 2000's hardware/sofware do for you on that end?
Sensitivity does improve over the decades, but increased sensitivity doesn't mean much if you dont improve the signal to noise ratio. the "sensitive" part of the modern digital receiver is the ADC. They have gotten more sensitive over the decades. But this benefit is useless if the background noise remains loud. Thus DSP noise reduction techniques are required to take any advantage of a more sensitive ADC.
Phase coded pulses (pulse compression) can be used to increase your SNR via a phase match filter, which can add upwards of 13dB of gain. However, those are mainly used with long range MPRF modes. Not HPRF. So if ur radar has HPRF, pulse compression wont be the deciding factor of your max detection range (HPRF > MPRF with phase coded pulses).
Larger FFTs (integrations) can increase SNR. For every pulse coherently integrated (pulse doppler radar), your gain increases by ~1dB. About .3 dB per pulse integrated non-coherently (non-pulse doppler radar).
Sidelobe cancelation increases SNR.
Minimizing signal loss can increase gain.
Radar cooling reduces heat at the receiver, decreasing noise, thus increasing SNR.
GaAs and GaN are semiconductors that perform well at high power with microwave (and millimeter wave) frequencies. I dont think they directly improve sensitivity per say. But they certainly enable AESA architectures which can employ advanced signal processing (DBF, TBD, adaptive nulling, STAP, etc) and provide low receiver loss since the ADCs are located close to the antenna. (waveguide antennas, like planar array and PESA, experience a lot of loss due to waveguide frequency response curves, internal reflection (non-perfect coupling), heat, and path loss) So in a sense, they indirectly improve receiver performance.
A pretty cool radar with a VERY sensitive receiver I know of is a actually an analog photonic radar. This radar doesn't down-convert the signal at all, thus reducing a lot of noise. The microwave energy is upconverted to near optical light, and processed via beam-slitters, fiber optics, etc.
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20 minutes ago, dundun92 said:
I know, my comparison was not HPRF to MPRF, but rather the high peak power MPRF of the APG-68 to the lower peak MPRF of other radars, specifically the APG-73
This means nothing if you dont know the duty cycle.
Peak power isnt even in the radar range equation. Average power is. If your radar has 20kw peak power at a 10% duty cycle, and my radar has 15kw peak power at a 20% duty cycle. My average power (3kw) will be higher than your average power (2kw).
Duty cycle can be calculated via Pulse Duration/Pulse Repetition Interval. Good luck finding those for the -68 and -73.
Also, power is one of the least significant variables to detection range. A common saying in the radar community is, "If you want to double your range, but you can only control one variable, you would need to increase your output power by 16x. But only 4x for antenna gain."
At the end of the day, antenna size, integration count, and sidelobe cancelation are more important than total output power. Especially if you're only talking about a few extra kw.
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On 6/9/2021 at 4:35 PM, dundun92 said:
Another note on the F-16 MPRF, and why its MPRF is so good. Because it doesnt use HPRF, they can get away with quite high peak powers compated to HPRF radars while keeping average power low. For reference, the APG-66 operates at a 21.5 kW peak power, and the 68 is at 17.5 kW. This contrasts to the AGP-63 which is 13 kW, with the AWG-9 in the same range. APG-65 is around 5 kW (hard to find an exact number though), as is the N001. So thats part of the tradeoff of optimizing for MPRF.
MPRF will never match the detection range performance of HPRF.. Ever.
A typical MPRF waveform only get to integrate 1/8 of the total 'time on target' due to the use 8 separate PRFs (typically). Each of the those PRFs gets sampled/integrated individually.
HPRF (with FMR for ranging; ie STT, RWS, TWS) gets to integrate about 1/3 of the total 'time on target' since it only has three segments in its waveform. (3 stage FMR)
On average, MPRF waveforms transmit about 20,000 pulses per second and HPRF about 200,000 pulses per second. Thus, HPRF can integrate many more pulses given the same integration period as MPRF. But as I explained above, HPRF has much longer integration periods than MPRF.
Without going into detail, a HPRF waveform will integrate on the order of many thousands of pulses, while MPRF will integrate on the order of hundreds of pulses.
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17 hours ago, jojo said:
You will have a better range in 1 line 20° scan than 4 lines 120° scan or even 80° scan.
And this is typically the 1 line & narrow scan range that you get in open source publications...Not really..
You dont get better range with a narrow scan IRL. You get more chances to 'roll the dice' as it were.
This is a misconception that I've heard real pilots say as well.
Unlike DCS, which has a black and white detection range, real life targets have a constantly fluctuating RCS. Depending on moment to moment geometries that light follows, the detection range against a target will too fluctuate. Typically the range provided by the manufacturer is the 50% probability of detection (Pd) aginst a Xm2 target. (ie the average detection range against an Xm2 target).
A good example would be if a radar was advertised to have a 50 nmi detection range against a 5m2 target. What this really means is that there is a 50% probability that the radar will detect a 5m2 target at 50nmi (under optimal conditions as well; ie look-up/head-on/HPRF).
In this example the radar would likely have 90% Pd at ~40nmi and ~10% at 60nmi.
A smaller scan doesn't change your output power, duty cycle, gain, receiver sensitivity, or # of pulses integrated. It just means that if the fluctuating geometries weren't in your favor, scanning over the target again and again; you may get lucky with a moment of high reflectivity.
Back on the topic of DCS:
Since DCS uses black and white detection ranges (ie they don't use probabilities; 100% or nothing) than they should be using ranges less than the advertised 50% ranges provided by manufacturers. (ie if Raytheon said that the APG-73 could see a fighter sized target 50 nmi away. DCS should use 40 nmi, since Raytheon is talking about 50% Pd while DCS is using 100%)
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Max range would be with HPRF.
HPRF waveforms don't use pulse compression. MPRF waveforms do, but not HPRF.
HPRF waveforms of this era use a three stage FMR.
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HPRF integration time per FMR stage is likely equal to:
3dB antenna beam width / (antenna scan in degrees/sec) / 3
This formula maximizes the integration time whilst being about to illuminate a single target with 3 separate waveforms (3 stage FMR)
Each FMR stage being its own integration period.
Generic example:
Antenna beam width = 3 degrees
Scan speed = 60 degrees per sec
(3 degrees) / (60degrees/sec) / 3 = .0167 sec integration time (per FMR stage)
Assume a 30% duty cycle in HPRF
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F-16 doesn't have HPRF in RWS/TWS.. Only MPRF. That alone means that the integration time and average power is much higher in the F-18.
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MPRF integration time is likely equal to one of several FFT sizes (64, 128, 256, 512) multiplied by the PRI.
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I know how to add them to the A-10, thanks to looking through the famous RAE mod.. But i dont think its possible to use the same technique to add them to the F-16 yet.
Couldnt add them to the viggen, bc it doesnt pull from premade audio files. Viggen uses some ancient CPU hex code to generate tones in real time. This reduces file size, but really limits what you can do with the tones (limited to a few tones, limited to sine waves, nothing over 7khz, no complex PRFs, no embedded sidelobe or AM)
F-5 would be a great module to add my tones to, but the C++ code under the hood doesn't allow me to just alter lua code to get it to work as it does in the A-10.
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realistic audio can be made.. You just need someone who understands Radar theory..
Below is a highly authentic Radar tone I made of an APQ-153, using the radar's parameters found online via an NASA document.
I've also made 'generic' tones (where the specific radar parameters are unavailable) using my extensive knowledge of radar waveforms and modulation types (MPRF dwell and switching, LPRF Jitters, etc).
In the post below was me describing some issues with the Viggen's RWR sounds. But at the bottom I show a generic MPRF tone I made for the Mirage 2000
We dont actually need real world radar parameters to accomplish RWR PRF tones. The intent is to make tones that are unique to a given radar system. ie an SA-2 FanSong should sound the same in the Viggens RWR as it does in any other RWR that provides PRF audio. Thats bc the PRF audio is based on the radar's parameters (PRF, Scan, Beamwidth/sidelobes), not the RWR.
Pilots of old could recognize a fanSong going into High PRF mode (about to engage) from the tone alone despite having migrated from the F-105 to the F-4.
Also, the RAE mod has some good, and some very poor RWR sounds.
I have a large library of tones I've made over the past few years that include PRF, PRF modulation, scan time, beamwidth and sidelobes. For example, for modern fighters i use a MPRF waveform picking 8 PRFs in a dwell and switch between 10khz - 100khz (as per the 'Introduction to Airborne Radar' book), using the known scan times, beamwdith and approximated sidelobes. I have each PRF dwell for 256 pulses (typical FFT count used by air radars, as per the book).
For each fighter radar I chose a different set of 8 PRFs.
I make two audio files for each. A search and a lock tone. the only difference being that the lock tone is continuous, while the search tone has the scan time and beamwdith implemented.
I take similar approaches to land based radar. Low PRF, stagger or jitter depending on technological era. Using videos to determine scan time.
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I made a post in this thread a few weeks ago about the Az/El page missing some features. It appears my post was removed.
Im curious if ED can confirm if the Az/El page will receive additional data, such as RWR, Jammers and Datalink in a future update? Thanks
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11 minutes ago, NineLine said:
As always, please supply references, even if it needs to be in PM. Thanks.
Sent
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GMT/SEA interleaved with RBGM (ground mapping) looks to have an issue.
Theyre correct in that the mode changes with each scan.. (ie scan right = GMT, scan left = Mapping)
But the data shouldn't be erased when the mode switches.
For instance, the map data should be frozen in the background when the GMT sweep is happening (not erased); and then updated when the mapping sweep occurs.
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So, ive read various sources that say the AWG9 was bad over land. Can anyone specifically explain to me why this should be given that its a pulse doppler radar?
@beamscanner
FYI, I dont search for threads with "beamscanner" in it. So i just now saw this.
There's a bunch of stuff getting tossed around that isn't completely accurate to your question.
- The AWG-9 was an analog pulse doppler radar. No FFTs (or DFTs) were performed.
- Physical band pass filters were used for doppler binning. These were tuned circuits made of inductors and capacitors. A lot of these were needed to account for all closing velocity scenarios.
- Band reject filters were used for notching out zero doppler (altitude line) and the main beam clutter return (this likely would have been a voltage controlled tuned circuit so that the band reject could be moved in freq with the scan of the antenna)
- MPRF wasn't around with analog radar because of practical size limitations. MPRF uses range and doppler bins to filter for targets. usually returns are filtered in time(range) first. Then each range bin has the entire series of doppler bins within. Thus, if an analog radar was to filter 100 doppler bins and 100 range bins, it would actually need 10,000 doppler bins (100 doppler bins per range bin). Each of those 10,000 bins being a physical tuned circuit. MPRF only became practical with digital signal processing where ADCs took the place of range bins, and FFTs were used in place of doppler bins. ie everything was done in code.
- An analog pulse doppler radar, only using HPRF (like the AWG-9), will only use doppler bins. And thus, given the same example above, would only use 100 doppler bins (FYI the AWG-9 likely used many more than 100, but this is just to compare the number of bins required for HPRF vs MPRF). As no range binning took place. In RWS/TWS HPRF modes, range is resolved post detection via FMR (freq modulated ranging).
- The AWG-9's overland performance was probably more dependent on the skill of the RIO than anything. Modern digital radar receivers can employ DSP techniques to reject much of the ground clutter. But digital receivers usually add thresholds which prevent noise like sources from entering. This also means that weak returns would be filtered out by the digital receiver. That threshold doesn't exist in analog radar. Instead, the RIO has a gain control which lets them control how much noise comes in. Todays DSP have certainly beat out the best of AWG-9 RIOs, but when comparing a 1980s airborne radar, like the APG-63v0, I think an above average RIO would win.
EDIT: my source for all of this is George stemson's intro to airborne radar. Which was originally an internal Hughes aircraft company handbook handed out to company engineers. Thus, much of the material contained within uses company products (like the AWG-9) as examples. There's even a picture of the bandpass filters (ie doppler bins) used on the AWG-9. They were about the size of a quarter, each.
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nice
Radar/PRF audio perhaps?
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Will the ALR-69 be updated in the Tank Killer module?
-Improved IP-1310 display? Needs some depth and a CRT effect (like the updated DDIs in the Hornet)
-RWR PRF audio library? Like what's being developed for the F-16C.
-Improved detection logic?
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I too have this problem..
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In addition to TWS AUTO and MAN scan centering(both of which are in OB), BIAS scan centering exists.
In Bias Scan Centering the pilot can adjust the scan center and antenna tilt with the HOTAS (just like MAN mode), but if a L&S / DT2 exist the scan movement is limited so that the L&S / DT2 cannot leave the scan.
EDIT: Bias scan is in the sim, but it does not keep the L&S in the scan.
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Please add these to the list:
TWS Hits: https://forums.eagle.ru/showthread.php?t=285300
Bias Scan Centering: https://forums.eagle.ru/showthread.php?p=4478456#post4478456
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The TWS "Hits" option should display "raw hit" target symbols on the radar display when the radar operating mode is TWS. The raw hit symbols are displayed at a lower intensity level than track file symbols at the same selected target aging.
Currently in DCS, Hits only shows raw hits for targets beyond the maximum 10 track files.
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I use a TM F18 grip on a Virpil T50 base with a Virpil 20cm extension, lovely combo.
hows the weight distribution with that combo? I understand that the TM hornet stick is heavy. Does the base+extension handle it well?
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I get that the MC will correlate different returns to create a trackfile, so I'm not sure if the trailing bricks are supposed to disappear like that or not, considering that the MC knows they probably belong to the same target (how it created the trackfile in the first place). Or if only the lead brick should disappear and become a HAFU. I just thought I'd mention it.
Not sure about RWS.. But I have seen a document on RAID mode show the brick trails remain in place with the trackfile in the lead.
"Spot" Mode Long-press Logic?
in Wish List
Posted
I think it should initiate without the need to release the button.