Hi Leon and all,
I'm looking at the
Si4464/63/61/60 data sheet
https://www.silabs.com/documents/public/data-sheets/Si4464-63-61-60.pdf
On Page 8 we have "Image Rejection" at only 35db and 55db corrected.
Since their IF is only 468KHz, it's not possible to filter it our with the RF
front end.
Would better Rx performance be had using a Superhet design. A 45MHz, 21.4MHz or
10.7MHz IF
where we use a crystal filter and 'completely' loose that image?
Alan VK2ZIW
On Fri, 9 Mar 2018 18:06:30 +0200, Leon Lessing wrote
> Hi all,
> I have about 90 pieces of stm32f405rgt which is the 64 pin device, I see it
> is "compatible" with the stm32f722
>
> Having worked a lot in the low volume/cost arm world, I have a pcb carrier
> roughly 1x3 inches, it has the usb plug on it and the xtal, swd etc.
>
> It helps you do extreme speed hardware development with minimal effort, so
> porting the design to another cpu it not a big issue.
>
> Yea I know it is an ugly shortcut, but it works well when your product must
> pass emc tests, well sometimes.
>
> Them RT1050 silicon looks damn cheap compared to the stm devices, a good
> reason not to use cubex :)
>
> Leon
>
>
>
> Leon Lessing
> 雷立安
> ZS6LMG/AC9GU
>
> On Fri, Mar 9, 2018 at 10:44 AM, glen english <g...@cortexrf.com.au> wrote:
> Agreed.
>
> skip the F4 and go straight to the F7 , unless cost is an issue.
>
> CODEC2 was almost 1.7x the speed on the F7 compared to F4 for same clock .
>
> The H7s are expensive, don't you think Danilo ? I am going RT1050 for next
> design.. $5. k
>
> On 9/03/2018 7:05 PM, Danilo Beuche wrote:
>
> Hi Leon,
>
> if you design with a STM32F4xx and 100 pin, I would recommend to choose one
> of the newer types (read STM32F469/STM32F479). They have a pinout compatible
> to the 100 pin STM32F7xx line (and it is only slightly different compared to
> the STM32F40x so a relayout shouldn't be hard). With this it would be trivial
> to drop in a much higher performance STM32F7xx without PCB redesign. The F7xx
> gives about twice as much performance as the F4xx with about the same amount
> of power used (that is our experience with the signal processing in the
> UHSDR/mcHF vs. UHSDR/OVI40 firmware builds). This restriction does apply for
> 100pin devices only. So if you used a 144 pin variant of the STM32F405,
> nothing to worry about.
>
> BTW, once the STM32H7 is really readily available, you get either even more
> processing power at 400 Mhz clock for about the same power usage or at the
> same clock rate similar performance but less power consumption due to
> shrinked MCU design (90 -> 40nm AFAIR).
>
> Danilo
>
> On 09.03.2018 07:00, Leon Lessing wrote:
> Hi all,
>
> Just bear with me here,
> My experience with some of the brandmeister guys has been less than
> spectacular. There is no reason we cannot use "dmr framing" and use codec2 to
> transmit stuff, effectively splitting a dmr channel into 4 potential codec2
> slots.
>
> I have revamped the adf7021 hotspot thing so it is more rf friendly, the
> design is unfortunately in eagle 7.7, mail me for a copy.
>
> This week I have been on holiday and struggling with the lora issue, but in
> the back of my mind I have been thinking mmdvm, hotspot hardware adf7021,
> sm1000 and 1296. I am about 90% finished with a mmdvm/sm1000/sdcard hybrid
> using a stm32f405.
>
> The code from mmdvm_hs uses bit banging to talk to the adf7021, I will add an
> adf7021 to the mix and maybe a rda1846, a gps and esp8266. Another idea is to
> break out the extra control lines and spi bus from the stm32f405 to a
> connector so we can build a stacked system. I'll publish the pcbs, I have no
> idea how we can use git or svn to share the pcb work.
>
> There is issues with the adf7021 and harmonics, this is why the commercial
> market uses R5000 (dedicated dmr framing) and the CML data pump devices. Dual
> band matching seems to be an issue with this device as well, I am trying to
> get the hotspot hardware to work on 145Mhz without harmonics on 290Mhz.
>
> Please mail me if you need a copy of the files for a peer design review, I
> will use dirtypcbs to do the dev run and give you guys the links and you can
> order pcbs, shipping from South Africa is terribly expensive.
>
> Look at the pine64 as an alternative to raspberries. The idea of doing a sdr
> radio is excellent, but mixer bleed through is a massive issue for the
> transmitting side. (most mixers gives 60db local suppression, but 60db down
> on +5dbm local inject is still a very strong signal)
>
> Regards,
> Leon
>
> Leon Lessing
> 雷立安
> ZS6LMG/AC9GU
>
>
>
> On Fri, Mar 9, 2018 at 1:31 AM, Adrian Musceac <kanto...@gmail.com
> <mailto:kanto...@gmail.com>> wrote:
>
> Hi Alan,
>
> >
> > I ask, how far are we in being able to completely replace the
> firmware
> > in the lowly MD-380 and clone radios? Or, could we beef up the
> power in
> > the 7021, already used in the project!!!!!!
> >
> That (as in running Codec2 2400A) will never happen for technical
> reasons.
>
> Using an SDR it's possible to have Codec2, C4FM, D-Star, DMR and
> whatever else on a single device.
>
> There exist handheld full SDR terminals with a price point of
> $800-$1000, capable of running almost everything you want up to high
> speed video. Documentation is close to zero, writing software for
> them
> would cost in the high 6 digits figures (not going to happen soon).
> Said terminals will go EOL in 4-5 years as public services transition
> to LTE.
>
> If you want to try some of the new digital modes without spending a
> fortune in equipment and DSP training, I suggest to invest some time
> in learning GNU radio. It's the only viable alternative. I managed to
> make for myself 4 types of Codec2 VHF modems using it. BPSK, QPSK,
> 2FSK and 4FSK. Enough to play with for a while. OP25 (a GNU radio
> project) has had P25, C4FM, D-Star and DMR for a while now. Combining
> them into a single, easy to use application is just a matter of time.
>
> Cheers,
> Adrian
>
>
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