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by jahboater
Tue Nov 13, 2018 10:24 am
Forum: Beginners
Topic: Antenna setup for aircraft signal advice
Replies: 23
Views: 470

Re: Antenna setup for aircraft signal advice

But the antenna is only 68mm long in one direction? The Pi3 antenna was for 2.4GHz. Frequency * Wavelength == 299792458 So the original antenna was 2.4 ghz, i trimmed it to 68mm which is 1/4 wavelength. How can i make a di pole from this existing antenna if it is just an antenna in 1 direction. I j...
by jahboater
Tue Nov 13, 2018 8:56 am
Forum: Beginners
Topic: Antenna setup for aircraft signal advice
Replies: 23
Views: 470

Re: Antenna setup for aircraft signal advice

DarkPlatinum wrote:
Tue Nov 13, 2018 8:20 am
jahboater wrote:
Mon Nov 12, 2018 10:58 pm
The old Pi3 antenna was a dipole!
But the antenna is only 68mm long in one direction?
The Pi3 antenna was for 2.4GHz. Frequency * Wavelength == 299792458
by jahboater
Tue Nov 13, 2018 7:40 am
Forum: Graphics programming
Topic: Divide By Depth??
Replies: 35
Views: 586

Re: Divide By Depth??

Ok I see the point of including floating point as standard, though SIMD should be optional. It seems that on modern computers they just use the first lane of the SIMD registers for the scalar floating-point registers. The latest Intel CPU's, have 512-bit registers and floats use the bottom 32 or 64...
by jahboater
Tue Nov 13, 2018 4:03 am
Forum: Graphics programming
Topic: Divide By Depth??
Replies: 35
Views: 586

Re: Divide By Depth??

I don't understand. Could you explain what you mean by "restrictive" or "non-restrictive" instruction set. What restrictions are we talking about? I believe this means "optional" features - similar to RISCV - in case a manufacturer wants to reduce power or cost. Since 2011 when ARMv8 was introduced...
by jahboater
Mon Nov 12, 2018 10:58 pm
Forum: Beginners
Topic: Antenna setup for aircraft signal advice
Replies: 23
Views: 470

Re: Antenna setup for aircraft signal advice

Thanks for your help so far. Which do you advise me to use, a 1/4 wavelength or 3/4 wavelength? I would just and the extra 2/4 wavelength onto my existing antenna (single pole). I can't really create my own antenna as I do not have and MCX connector. All I can really do is make my existing antenna ...
by jahboater
Mon Nov 12, 2018 8:36 pm
Forum: Beginners
Topic: Antenna setup for aircraft signal advice
Replies: 23
Views: 470

Re: Antenna setup for aircraft signal advice

Would a longer antenna be better then a shorter antenna? Wow - a *big* question! Talking about omni-directional vertical antennas (briefly) .... The captured signal goes up with the square of the length. However, the antenna must be a correct fraction of the wavelength for the frequency of interest...
by jahboater
Mon Nov 12, 2018 8:18 pm
Forum: General discussion
Topic: Programming Software for Raspberry PI
Replies: 11
Views: 272

Re: Programming Software for Raspberry PI

AFAIK Python 3 is *not* installed on Lite. It's installed in pi-gen stage 4. Lite does not go further than stage 2 https://github.com/RPi-Distro/pi-gen/blob/master/stage4/00-install-packages/00-packages Python 3 is included with Lite: [email protected]:~ $ python3 Python 3.5.3 (default, Sep 27 2018, 17:25:39)...
by jahboater
Mon Nov 12, 2018 7:07 pm
Forum: General discussion
Topic: Programming Software for Raspberry PI
Replies: 11
Views: 272

Re: Programming Software for Raspberry PI

adigitaldj1 wrote:
Mon Nov 12, 2018 6:39 pm
Can I program from Windows 10 and send it to the PI, like Arduino or do I have to program within Raspbian for example?
You can do either.
IMHO its far far easier to program on the Pi itself.
by jahboater
Mon Nov 12, 2018 7:04 pm
Forum: General discussion
Topic: Programming Software for Raspberry PI
Replies: 11
Views: 272

Re: Programming Software for Raspberry PI

If you install the Raspbian operating system (not the lite version) or pretty much any other Linux based OS it will have compilers for C and C++ and Python run times already installed ready to use. Anything that is missing can be added in seconds with the package manager. Are you sure that gcc isn'...
by jahboater
Mon Nov 12, 2018 4:27 pm
Forum: Graphics programming
Topic: Divide By Depth??
Replies: 35
Views: 586

Re: Divide By Depth??

jamesh wrote:
Mon Nov 12, 2018 4:04 pm
Are there any current SoC scale ARM devices without FPU's? Not talking M0 type of stuff, but cores that go on SBC's.
I don't know of any, but I haven't done an exhaustive search!
by jahboater
Mon Nov 12, 2018 4:02 pm
Forum: Graphics programming
Topic: Divide By Depth??
Replies: 35
Views: 586

Re: Divide By Depth??

The Pi2, Pi3 and Pi3+ have ARMv8 CPU's - and for ARMv8, floating point/SIMD is no longer a co-processor, it is built in to the ARM core. So VFP and NEON is not even an option for the bigger Pi's, it is guaranteed to be present. That is for the RPi, not so much for other systems. No, it is true for ...
by jahboater
Mon Nov 12, 2018 3:31 pm
Forum: Graphics programming
Topic: Divide By Depth??
Replies: 35
Views: 586

Re: Divide By Depth??

The pure ARM core has FP? I thought that FP was only in the optional extensions like VFP/NEON, is there something I do not know? I think what you mean is that for the older ARM CPU's, the floating point unit was an optional co-processor. All Pi models from day one had this co-processor, so they all...
by jahboater
Mon Nov 12, 2018 10:30 am
Forum: Beginners
Topic: Antenna setup for aircraft signal advice
Replies: 23
Views: 470

Re: Antenna setup for aircraft signal advice

It does not look like I can reach the tv satellite cable since it is being fed into the roof of my house. Would I be able to make an antenna with standard circuit/ electrical cable? Yes, as a simple and cheap experiment. Don't expect it to perform as well as a purpose made antenna with the correct ...
by jahboater
Sun Nov 11, 2018 2:27 pm
Forum: Off topic discussion
Topic: What was your first computer?
Replies: 384
Views: 94718

Re: What was your first computer?

mymanga003 wrote:
Sat Nov 10, 2018 3:25 am
My first PC I on was a gigantic Mainframe at a Burroughs.
On that basis I claim a CDC 7600 super computer.
Replaced later by a Cray 1 ...

OK, it was one job per day, punched cards ....
by jahboater
Sun Nov 11, 2018 2:24 pm
Forum: Python
Topic: How to read the last line from a file?
Replies: 5
Views: 149

Re: How to read the last line from a file?

Also "tail -1 file"
by jahboater
Sat Nov 10, 2018 7:49 am
Forum: Off topic discussion
Topic: Cortex-A72 compared to Pi 3B+
Replies: 23
Views: 657

Re: Cortex-A72 compared to Pi 3B+

DavidS wrote:
Sat Nov 10, 2018 6:42 am
ejolson wrote:
Sat Nov 10, 2018 2:23 am
Still wondering about A72 versus Pi 3B+ performance.
Well that is a tough one indeed, if the A72 is a 64 bit only implementation then comparison becomes difficult.
We are OK there, its only the recent A76 and friends that are 64-bit only.
The A72 is quite old in this context, announced 2015.
by jahboater
Fri Nov 09, 2018 7:14 pm
Forum: RISCOS
Topic: RISC OS now under the Apache 2.0 Licence
Replies: 29
Views: 905

Re: RISC OS now under the Apache 2.0 Licence

OK this puts me a bit behind. I thought they were still ARMv8 which last I read requires 32-bit support. Though it does not make any sence to go pure 64-bit with any CPU, this seems like a significant issue, as more applications would benifit from 32 bit registers than 64-bit. And memory capacity i...
by jahboater
Fri Nov 09, 2018 5:11 pm
Forum: RISCOS
Topic: RISC OS now under the Apache 2.0 Licence
Replies: 29
Views: 905

Re: RISC OS now under the Apache 2.0 Licence

Yes it is written largely in assembler. This is not a problem for its future, so long as we have ARM CPU's capable of running in 32 bit modes. Now if they ever decide to go purely 64-bit this could be an issue, The recent ARM cpu's (such as the Cortex-A76) are 64-bit only. However, RISC OS is fast ...
by jahboater
Fri Nov 09, 2018 4:44 pm
Forum: RISCOS
Topic: RISC OS now under the Apache 2.0 Licence
Replies: 29
Views: 905

Re: RISC OS now under the Apache 2.0 Licence

I think the OS system calls provide graphics directly. Which is pretty cool.

But its mostly written in (old) assembler, so I speculate that its long term future is in doubt.
by jahboater
Fri Nov 09, 2018 3:31 pm
Forum: Off topic discussion
Topic: Cortex-A72 compared to Pi 3B+
Replies: 23
Views: 657

Re: Cortex-A72 compared to Pi 3B+

jamesh wrote:
Fri Nov 09, 2018 3:16 pm
You also need to take in to account the process node used. The Pi3 SoC is on 40nm, whilst most A72 designed S0C's are on 28 or lower, and that makes a difference to the power requirements.
Wow, I see the A76 is 7nm!
by jahboater
Fri Nov 09, 2018 1:23 pm
Forum: Troubleshooting
Topic: Install / Boot Problems and how I resolved it
Replies: 2
Views: 93

Re: Install / Boot Problems and how I resolved it

- Use of Windows 10 to prepare the SD Card. You can use any popular OS - Windows, Linux, MacOS (I use Linux because no special tools need be installed). - Formatting the card with "SD Card Formatter 5.0.0" by Tuxera Inc. (Quick Format did the job) Not needed. The next step overwrites any formatting...
by jahboater
Wed Nov 07, 2018 11:07 pm
Forum: Raspbian
Topic: Large, (128GB) SSD install
Replies: 11
Views: 2139

Re: Large, (128GB) SSD install

puccaso wrote:
Mon Nov 05, 2018 6:57 pm
I also want to install on a 128GB SSD but should i be formatting an 128GB SSD as msdos format?
Don't format it at all.
+3 to the posts saying use a simple Raspbain image from
https://www.raspberrypi.org/downloads/raspbian/
and forget NOOB's ever existed.
by jahboater
Wed Nov 07, 2018 6:13 pm
Forum: Raspbian
Topic: Is /tmp ramdisk in Raspbian?
Replies: 4
Views: 132

Re: Is /tmp ramdisk in Raspbian?

All my Pi's (including Pi Zero's) have these two lines added to /etc/fstab tmpfs /tmp tmpfs defaults,noatime,nosuid 0 0 tmpfs /var/log tmpfs defaults,noatime,nosuid,size=16m 0 0 The default maximum size is half the memory, but of course tmpfs only takes as much memory as the files need. While you ar...
by jahboater
Wed Nov 07, 2018 7:51 am
Forum: General discussion
Topic: 64-bit operating system
Replies: 180
Views: 15455

Re: 64-bit operating system

The phrase "Must have 64bit for learning" is nonsense. Saying "32 bits is OK for kids" shows a massive misunderstanding and is just a bit insulting to children and adults alike. Er, I meant "must have" for my personal learning, specifically Aarch64/NEON coding. In the short time I have left (a deca...
by jahboater
Tue Nov 06, 2018 11:11 pm
Forum: General discussion
Topic: 64-bit operating system
Replies: 180
Views: 15455

Re: 64-bit operating system

The next one I learned an assembly language (COMPASS) on used 60-bit words (no, that's not a typo. six-zero bits per word). The Control Data 7600 super computer I used had 60-bit words. Later a Honeywell-6000 mainframe had 36-bit words (which I did quite a lot of assembler on). This modern obsessio...

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