Home security device manufacturers in the UK are required to adhere to a complicated set of British and European standards before their products can hit the market, which typically requires professional installation. A consequence of this relatively high barrier to entry is that most of the available alarm solutions are professional grade and, due to these regulations, must be segregated from other smart home assistance. Scotland-based Boundary is working on bridging this gap with a state-of-the-art alarm system that consumers can install themselves and monitor through their smartphones. We recently sat down with Boundary co-founder, Paul Walton to learn more.
Tell Us About Boundary.
Boundary was founded in 2018 after a successful Kickstarter campaign, producing a smart intruder alarm system for the UK market based on Z-Wave technology. Our co-founder, Robin Knox, had the idea when he was on his honeymoon and realized the limitations of his existing alarm system meant that if his home was broken into, he would be unable to actually do anything other than watch the events unfold on a CCTV camera. Immediately upon his return, he set out to find a reasonably priced self-install security system but had little success. This gap in the market for DIY home security was the catalyst to build something that looked great, was user-friendly, and provided better features at a reasonable price point.
Internally, our company’s goal was to develop a great mobile app that provided a much more intuitive and enjoyable user experience. With a focus on the user journey and hardware design, we are anticipating launching our first product, a smart IoT alarm system, this month. This system consists of four components: the central hub (which is the Z-Wave gateway), a motion sensor, a contact sensor, and an external siren, all of which connect to the central hub advisory.
One thing that sets Boundary apart from our competitors is its EN50131 European Standard for Intruder Alarm Systems compliance certification. Achieving this level of certification requires some pretty tough validation, dropping the hub from two meters and making sure that it's still operational, for instance. The rigorous design detail has made us the first manufacturer of a Z-Wave 700 device that is currently undergoing this certification, which is expected to be completed in the first quarter of next year.
Why Did You Choose Silicon Labs Z-Wave Solutions for Your Products?
When it came to selection criteria, we had many requirements that needed to be met. Some were driven by the standards and some were simply a matter of the target data transmission rates the team wanted to meet. Developing a product that did not require complicated setup and provided the range required to cover a medium-to-large sized house was also important, as was maintaining connection for all devices on the network. Z-Wave emerged as the standard that could meet these challenges. Set-up is incredibly simple, requiring the customer to simply scan a QR code to pair the device.
The result is an alarm that is easy to use and exceeds the highest regulatory standards. Our product features a motion sensor with always-on detection that can be used for home automation routines like powering down smart lighting and regulating heating when a room is not in use. With a door/window sensor, any unauthorized entry will immediately set off the alarm. Users can also see the status of a window or door from the app at any time.
Looking Forward, Where Do You See the Smart Home Security Market Heading?
We believe that within the next five years, we’ll see a bit of a shift in the home security market towards proactive security. For Boundary, our focus is on bringing another product to market, one that utilizes machine vision, and to expand into Europe.
For more information on how Boundary used Silicon Labs Z-Wave solutions to deliver professional-grade security to smart homes, check out our case study and learn more about smart home offerings. If you’d like to leverage the benefits of Z-Wave technology for your smart home applications, we’d love to hear from you.
In the previous Timing 201 article, Timing 201 #7: The Case of the Dueling PLLs – Part 1, I referred to a Silicon Labs white paper that describes Silicon Labs’ DSPLL nested dual-loop architecture as used in the Si538x wireless jitter attenuators. I first discussed the general motivation for a dual-loop PLL and compared the cascaded (series) dual-loop PLL versus the nested dual-loop PLL architectures.
The practical advantages of the nested dual-loop approach in this example were to reduce the number of tuned oscillators from 2 to 1 and to eliminate the need for a sensitive external voltage control line. The tradeoff for a nested feedback control loop is that the inner loop must be faster than the outer loop. If the loop speeds (or bandwidths) are comparable, then the loops will contend or “duel” with each other.
In this Part 2 follow-up post, I will discuss in more detail how to calculate the phase noise of both these dual-loop PLL approaches.
Some Simplifying Assumptions
To emphasize the basic ideas without getting bogged down in too much detail, I will make the following simplifying assumptions:
Series Dual-Loop Phase Noise Calculations
The figure below is from the cited white paper and previous post. The two PLLs are in series with each other.
You will recall that the first PLL, PLL1, is narrowband (NB) and the second PLL, PLL2, is wideband. To calculate the phase noise, we will go left to right through the following steps.
These calculations have been done in the attached spreadsheet Timing_201_7_The_Case_of_the_Dueling_PLLs - Part 2.xlsx. See the “Series Dual-Loop” worksheet. The PLLs are assumed to be 2nd order with the NB PLL BW = 100 Hz and the WB PLL BW = 1 MHz. These parameters can be changed in the spreadsheet, but practically speaking, NB PLLs will be on the order of mHz to kHz. WB PLLs are typically 500 kHz to 2 MHz.
The resulting plot is as follows.
Nested Dual-Loop Phase Noise Calculations
The figure below is also repeated from the cited white paper and previous post. In this case, the two PLLs are nested with respect to each other.
Now the inner loop (IL) PLL is WB and the outer loop (OL) PLL is NB. To calculate the phase noise, we will proceed from the “inside out” through the following steps.
These calculations have also been done in the attached spreadsheet Timing_201_7_The_Case_of_the_Dueling_PLLs - Part 2.xlsx. As before, to keep things “apples to apples”, the PLLs are assumed to be 2nd order with the NB PLL BW = 100 Hz and the WB PLL BW = 1 MHz. See the “Nested Dual-Loop” worksheet. The resulting plot is as follows.
You will note how similar these plots are to each other. Let’s overlay the output phase noise plots together for comparison.
Series versus Nested Dual-Loop Phase Noise Plots
The output phase noise plots are overlaid on top of each other for direct comparison. As shown, they look identical. Further, if you experiment with the bandwidths of each PLL, for each topology, the best output phase noise is generally obtained by making PLL1 (or OL PLL) and PLL2 (or IL PLL) narrowband and wideband respectively. Even apart from stability considerations, both topologies benefit from wide separation between the bandwidths.
Why the Topological Equivalence?
This result is not necessarily to be expected so let’s walk through the steps again and compare the approaches.
LPF_WB (LPF_NB (Input) + HPF_NB (VCXO)) + HPF_WB (VCO)
LPF_WB * LPF_NB (Input) + LPF_WB * HPF_NB (VCXO) + HPF_WB (VCO)
The use of WB and NB notation versus PLL1, PLL2, IL PLL, and OL PLL is to help us make direct comparison between the two sets of calculations. LPF_WB means apply a wideband low pass filter to the phase noise in parenthesis. Two filter terms multiplied indicates applying both filters.
LPF_NB (Input) + HPF_NB (LPF_WB (XO) + HPF_WB (VCO))
LPF_NB (Input) + HPF_NB * LPF_WB (XO) + HPF_NB * HPF_WB (VCO)
LPF_WB * LPF_NB (Input) ≈ LPF_NB (Input)
HPF_NB * HPF_WB (VCO) ≈ HPF_WB (VCO)
In other words, the NB LPF and the WB HPF dominate the calculations for these LPF and HPF terms. This is why these topologies produce equivalent total phase noise when all else is equal.
I hope you have enjoyed this Timing 201 article. In this Part 2 follow-up post, I have discussed in more detail how to calculate the phase noise of both the series and nested dual-loop approaches. Finally, by using a simplified example with widely separated bandwidths, we can see that the approaches are essentially equivalent. There are particular advantages to the nested dual-loop approach which arise from an alternate practical implementation that yields phase noise equivalent to the series dual-loop approach.
As always, if you have topic suggestions or questions appropriate for this blog, please send them to firstname.lastname@example.org with the words Timing 201 in the subject line. I will give them consideration and see if I can fit them in. Thanks for reading. Keep calm and clock on.